SELECT 
  cscart_product_prices.product_id, 
  MIN(
    IF(
      cscart_product_prices.percentage_discount = 0, 
      cscart_product_prices.price, 
      cscart_product_prices.price - (
        cscart_product_prices.price * cscart_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_product_prices 
WHERE 
  cscart_product_prices.product_id IN (
    597, 584, 573, 561, 556, 553, 549, 545, 
    541, 525, 521, 517, 513, 507, 497, 492, 
    489, 486, 482, 455, 453, 452, 451, 450, 
    449, 448, 447, 446, 445, 444, 443, 442, 
    394, 378
  ) 
  AND cscart_product_prices.lower_limit = 1 
  AND cscart_product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  cscart_product_prices.product_id

Query time 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "23.81"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "cscart_product_prices",
        "access_type": "range",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "key": "product_id",
        "used_key_parts": [
          "product_id"
        ],
        "key_length": "3",
        "rows_examined_per_scan": 34,
        "rows_produced_per_join": 6,
        "filtered": "19.93",
        "index_condition": "(`betaatif_store`.`cscart_product_prices`.`product_id` in (597,584,573,561,556,553,549,545,541,525,521,517,513,507,497,492,489,486,482,455,453,452,451,450,449,448,447,446,445,444,443,442,394,378))",
        "cost_info": {
          "read_cost": "23.13",
          "eval_cost": "0.68",
          "prefix_cost": "23.81",
          "data_read_per_join": "162"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`betaatif_store`.`cscart_product_prices`.`lower_limit` = 1) and (`betaatif_store`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}