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 (
    185415, 185391, 185376, 185375, 185380, 
    185377, 185395, 185385, 185416, 185379, 
    185392, 185393, 185386, 185422, 185378, 
    185402, 185388, 185383, 185425, 185382, 
    185400, 185394, 185403, 185387, 185381, 
    185409, 185419, 185397, 185384, 185413, 
    185429, 185424, 185411, 185423, 185421, 
    185404, 185398, 185399, 185407, 185412, 
    185405, 185414, 185418, 185396, 185427, 
    185417, 185428, 185406, 185408, 185431, 
    185389, 185390, 185401, 185426, 185432, 
    185420, 185430, 185410
  ) 
  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 0.00204

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "162.58"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "cscart_product_prices",
        "access_type": "range",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "key": "usergroup",
        "used_key_parts": [
          "product_id",
          "usergroup_id",
          "lower_limit"
        ],
        "key_length": "9",
        "rows_examined_per_scan": 116,
        "rows_produced_per_join": 116,
        "filtered": "100.00",
        "cost_info": {
          "read_cost": "139.39",
          "eval_cost": "23.20",
          "prefix_cost": "162.59",
          "data_read_per_join": "7K"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`webmarco`.`cscart_product_prices`.`lower_limit` = 1) and (`webmarco`.`cscart_product_prices`.`product_id` in (185415,185391,185376,185375,185380,185377,185395,185385,185416,185379,185392,185393,185386,185422,185378,185402,185388,185383,185425,185382,185400,185394,185403,185387,185381,185409,185419,185397,185384,185413,185429,185424,185411,185423,185421,185404,185398,185399,185407,185412,185405,185414,185418,185396,185427,185417,185428,185406,185408,185431,185389,185390,185401,185426,185432,185420,185430,185410)) and (`webmarco`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}