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 (
    15147, 15477, 2640, 12975, 11118, 12685, 
    2566, 3215, 3214, 15154, 13222, 14298, 
    13223, 16052, 2733, 2736, 2734, 2735, 
    15140, 2829, 2659, 14661, 15424, 2681, 
    2770, 2771, 2731, 15130, 17301, 15153
  ) 
  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 0.00147

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "24.16"
    },
    "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": 37,
        "rows_produced_per_join": 5,
        "filtered": "14.40",
        "index_condition": "(`dev_yourmart_co_bw`.`cscart_product_prices`.`product_id` in (15147,15477,2640,12975,11118,12685,2566,3215,3214,15154,13222,14298,13223,16052,2733,2736,2734,2735,15140,2829,2659,14661,15424,2681,2770,2771,2731,15130,17301,15153))",
        "cost_info": {
          "read_cost": "23.63",
          "eval_cost": "0.53",
          "prefix_cost": "24.16",
          "data_read_per_join": "127"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`dev_yourmart_co_bw`.`cscart_product_prices`.`lower_limit` = 1) and (`dev_yourmart_co_bw`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}