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 (
    8373, 8377, 8403, 8431, 8443, 8517, 8587, 
    8596, 8600, 8607, 8700, 8798, 10246, 
    11632, 7837, 7864, 8271, 8274, 8278, 
    8279, 8285, 8287, 8330, 8333, 8374, 
    8389, 8405, 8430, 8516, 8518, 8537, 
    8571, 8584, 8588, 8726, 8728, 8755, 
    8803, 10044, 10085
  ) 
  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 0.00112

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "32.51"
    },
    "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": 50,
        "rows_produced_per_join": 9,
        "filtered": "19.99",
        "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`product_id` in (8373,8377,8403,8431,8443,8517,8587,8596,8600,8607,8700,8798,10246,11632,7837,7864,8271,8274,8278,8279,8285,8287,8330,8333,8374,8389,8405,8430,8516,8518,8537,8571,8584,8588,8726,8728,8755,8803,10044,10085))",
        "cost_info": {
          "read_cost": "31.51",
          "eval_cost": "1.00",
          "prefix_cost": "32.51",
          "data_read_per_join": "239"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`lower_limit` = 1) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}