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 (
    34, 32, 31, 30, 29, 28, 8, 9, 10, 11, 12, 
    13
  )

Query time 0.00061

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "39.53"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "gpf",
          "access_type": "index",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "feature_id",
            "group_id"
          ],
          "key_length": "6",
          "rows_examined_per_scan": 53,
          "rows_produced_per_join": 12,
          "filtered": "22.64",
          "using_index": true,
          "cost_info": {
            "read_cost": "4.73",
            "eval_cost": "1.20",
            "prefix_cost": "5.93",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "feature_id",
            "group_id"
          ],
          "attached_condition": "(`betaatif_store`.`gpf`.`group_id` in (34,32,31,30,29,28,8,9,10,11,12,13))"
        }
      },
      {
        "table": {
          "table_name": "gp",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "betaatif_store.gpf.group_id"
          ],
          "rows_examined_per_scan": 4,
          "rows_produced_per_join": 48,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "12.00",
            "eval_cost": "4.80",
            "prefix_cost": "22.73",
            "data_read_per_join": "768"
          },
          "used_columns": [
            "product_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": 48,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "12.00",
            "eval_cost": "4.80",
            "prefix_cost": "39.53",
            "data_read_per_join": "37K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "lang_code"
          ]
        }
      }
    ]
  }
}

Result

feature_id product_id variant_id group_id
2 454 6 8
2 455 7 8
2 401 9 8
2 402 6 9
2 453 7 9
2 404 9 9
2 406 6 10
2 452 7 10
2 408 9 10
2 409 6 11
2 451 7 11
2 411 9 11
2 412 6 12
2 450 7 12
2 414 9 12
2 415 6 13
2 449 7 13
2 417 9 13
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
2 496 6 32
2 497 7 32
2 498 9 32
2 499 11 32
2 506 9 34
2 507 12 34
2 505 7 34
2 504 6 34