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 (
    1517, 1518, 1519, 1520, 1521, 1522, 1523, 
    1524, 1525, 1537, 1538, 1539, 1540, 
    1541, 1542, 1543, 1544, 1545, 2217, 
    2218, 2219, 2735, 2863, 2864, 3729, 
    3732, 5220, 5221, 5222, 5223, 5224, 
    5225, 5226, 5227, 5237, 5238, 5239, 
    5240, 5241, 5242, 5243, 5244, 5817, 
    5818, 5819, 6322, 6448, 6449, 7494, 
    7495, 7498, 7499, 7504, 7505, 7526, 
    7527
  ) 
  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 0.00109

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "39.66"
    },
    "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": 57,
        "rows_produced_per_join": 11,
        "filtered": "20.00",
        "index_condition": "(`gaseus`.`cscart_product_prices`.`product_id` in (1517,1518,1519,1520,1521,1522,1523,1524,1525,1537,1538,1539,1540,1541,1542,1543,1544,1545,2217,2218,2219,2735,2863,2864,3729,3732,5220,5221,5222,5223,5224,5225,5226,5227,5237,5238,5239,5240,5241,5242,5243,5244,5817,5818,5819,6322,6448,6449,7494,7495,7498,7499,7504,7505,7526,7527))",
        "cost_info": {
          "read_cost": "38.52",
          "eval_cost": "1.14",
          "prefix_cost": "39.66",
          "data_read_per_join": "273"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`gaseus`.`cscart_product_prices`.`lower_limit` = 1) and (`gaseus`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}