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SELECT 
  pfv.feature_id, 
  pfv.product_id, 
  pfv.variant_id, 
  gp.group_id 
FROM 
  cscart_product_features_values AS pfv 
  INNER JOIN cscart_product_variation_group_products AS gp ON pfv.product_id = gp.product_id 
  INNER JOIN cscart_product_variation_group_features AS gpf ON gpf.group_id = gp.group_id 
  AND gpf.feature_id = pfv.feature_id 
WHERE 
  pfv.lang_code = 'ar' 
  AND gp.group_id IN (
    31, 30, 29, 28, 8, 9, 10, 11, 12, 13, 14, 
    16, 17, 18, 19, 20, 21, 6, 3
  )

Query time 0.00097

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "56.71"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "gp",
          "access_type": "index",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "product_id",
            "group_id"
          ],
          "key_length": "6",
          "rows_examined_per_scan": 190,
          "rows_produced_per_join": 53,
          "filtered": "27.89",
          "using_index": true,
          "cost_info": {
            "read_cost": "14.32",
            "eval_cost": "5.30",
            "prefix_cost": "19.62",
            "data_read_per_join": "848"
          },
          "used_columns": [
            "product_id",
            "group_id"
          ],
          "attached_condition": "(`betaatif_store`.`gp`.`group_id` in (31,30,29,28,8,9,10,11,12,13,14,16,17,18,19,20,21,6,3))"
        }
      },
      {
        "table": {
          "table_name": "gpf",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "betaatif_store.gp.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 53,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "13.25",
            "eval_cost": "5.30",
            "prefix_cost": "38.17",
            "data_read_per_join": "5K"
          },
          "used_columns": [
            "feature_id",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "pfv",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "fl",
            "lang_code",
            "product_id",
            "fpl",
            "idx_product_feature_variant_id"
          ],
          "key": "fpl",
          "used_key_parts": [
            "feature_id",
            "product_id",
            "lang_code"
          ],
          "key_length": "12",
          "ref": [
            "betaatif_store.gpf.feature_id",
            "betaatif_store.gp.product_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 53,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "13.25",
            "eval_cost": "5.30",
            "prefix_cost": "56.72",
            "data_read_per_join": "40K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

feature_id	product_id	variant_id	group_id
2	124	12	3
2	378	8	3
2	379	9	3
2	391	8	6
2	393	12	6
2	394	9	6
2	401	9	8
2	402	6	9
2	404	9	9
2	406	6	10
2	408	9	10
2	409	6	11
2	411	9	11
2	412	6	12
2	414	9	12
2	415	6	13
2	417	9	13
2	418	6	14
2	420	9	14
2	424	6	16
2	426	9	16
2	427	6	17
2	429	9	17
2	430	6	18
2	432	9	18
2	433	6	19
2	435	9	19
2	436	6	20
2	438	9	20
2	439	6	21
2	441	9	21
2	442	7	21
2	443	7	20
2	444	7	19
2	445	7	18
2	446	7	17
2	447	7	16
2	448	7	14
2	449	7	13
2	450	7	12
2	451	7	11
2	452	7	10
2	453	7	9
2	454	6	8
2	455	7	8
2	480	6	28
2	481	7	28
2	482	9	28
2	483	11	28
2	484	6	29
2	485	7	29
2	486	9	29
2	487	11	29
2	488	6	30
2	489	7	30
2	490	9	30
2	491	11	30
2	492	6	31
2	493	7	31
2	494	9	31
2	495	11	31

feature_id	product_id	variant_id	group_id
2	124	12	3
2	378	8	3
2	379	9	3
2	391	8	6
2	393	12	6
2	394	9	6
2	401	9	8
2	402	6	9
2	404	9	9
2	406	6	10
2	408	9	10
2	409	6	11
2	411	9	11
2	412	6	12
2	414	9	12
2	415	6	13
2	417	9	13
2	418	6	14
2	420	9	14
2	424	6	16
2	426	9	16
2	427	6	17
2	429	9	17
2	430	6	18
2	432	9	18
2	433	6	19
2	435	9	19
2	436	6	20
2	438	9	20
2	439	6	21
2	441	9	21
2	442	7	21
2	443	7	20
2	444	7	19
2	445	7	18
2	446	7	17
2	447	7	16
2	448	7	14
2	449	7	13
2	450	7	12
2	451	7	11
2	452	7	10
2	453	7	9
2	454	6	8
2	455	7	8
2	480	6	28
2	481	7	28
2	482	9	28
2	483	11	28
2	484	6	29
2	485	7	29
2	486	9	29
2	487	11	29
2	488	6	30
2	489	7	30
2	490	9	30
2	491	11	30
2	492	6	31
2	493	7	31
2	494	9	31
2	495	11	31

feature_id	product_id	variant_id	group_id
2	124	12	3
2	378	8	3
2	379	9	3
2	391	8	6
2	393	12	6
2	394	9	6
2	401	9	8
2	402	6	9
2	404	9	9
2	406	6	10
2	408	9	10
2	409	6	11
2	411	9	11
2	412	6	12
2	414	9	12
2	415	6	13
2	417	9	13
2	418	6	14
2	420	9	14
2	424	6	16
2	426	9	16
2	427	6	17
2	429	9	17
2	430	6	18
2	432	9	18
2	433	6	19
2	435	9	19
2	436	6	20
2	438	9	20
2	439	6	21
2	441	9	21
2	442	7	21
2	443	7	20
2	444	7	19
2	445	7	18
2	446	7	17
2	447	7	16
2	448	7	14
2	449	7	13
2	450	7	12
2	451	7	11
2	452	7	10
2	453	7	9
2	454	6	8
2	455	7	8
2	480	6	28
2	481	7	28
2	482	9	28
2	483	11	28
2	484	6	29
2	485	7	29
2	486	9	29
2	487	11	29
2	488	6	30
2	489	7	30
2	490	9	30
2	491	11	30
2	492	6	31
2	493	7	31
2	494	9	31
2	495	11	31

feature_id	product_id	variant_id	group_id
2	124	12	3
2	378	8	3
2	379	9	3
2	391	8	6
2	393	12	6
2	394	9	6
2	401	9	8
2	402	6	9
2	404	9	9
2	406	6	10
2	408	9	10
2	409	6	11
2	411	9	11
2	412	6	12
2	414	9	12
2	415	6	13
2	417	9	13
2	418	6	14
2	420	9	14
2	424	6	16
2	426	9	16
2	427	6	17
2	429	9	17
2	430	6	18
2	432	9	18
2	433	6	19
2	435	9	19
2	436	6	20
2	438	9	20
2	439	6	21
2	441	9	21
2	442	7	21
2	443	7	20
2	444	7	19
2	445	7	18
2	446	7	17
2	447	7	16
2	448	7	14
2	449	7	13
2	450	7	12
2	451	7	11
2	452	7	10
2	453	7	9
2	454	6	8
2	455	7	8
2	480	6	28
2	481	7	28
2	482	9	28
2	483	11	28
2	484	6	29
2	485	7	29
2	486	9	29
2	487	11	29
2	488	6	30
2	489	7	30
2	490	9	30
2	491	11	30
2	492	6	31
2	493	7	31
2	494	9	31
2	495	11	31