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 (
    185427, 185417, 269958, 269940, 270142, 
    185428, 185406, 269931, 185408, 185431, 
    269959, 269964, 270144, 185389, 265428, 
    185390, 269978, 185401, 270132, 185426, 
    270133, 269983, 185432, 265408, 270023, 
    392330, 270131, 270134, 269965, 185420, 
    265401, 270017, 185430, 270015, 270087, 
    185410, 265420, 392264, 265465, 435508, 
    270057, 392324, 392270, 392314, 392272, 
    392325, 392273, 392329, 392317, 392326, 
    392332, 392333, 392335, 392313, 392319, 
    392328, 392323, 392262, 392320, 392316, 
    392271, 432460, 392331, 392266, 432542, 
    392268, 392274, 392275, 392327, 392321, 
    392334, 392322, 392315, 432333, 432589, 
    392312, 432449, 432642, 435503, 432353, 
    432668, 435523, 432523, 432251, 432652, 
    432688, 432320, 432694, 435520
  ) 
  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 0.00377

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "249.48"
    },
    "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": 178,
        "rows_produced_per_join": 178,
        "filtered": "100.00",
        "cost_info": {
          "read_cost": "213.88",
          "eval_cost": "35.60",
          "prefix_cost": "249.48",
          "data_read_per_join": "11K"
        },
        "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 (185427,185417,269958,269940,270142,185428,185406,269931,185408,185431,269959,269964,270144,185389,265428,185390,269978,185401,270132,185426,270133,269983,185432,265408,270023,392330,270131,270134,269965,185420,265401,270017,185430,270015,270087,185410,265420,392264,265465,435508,270057,392324,392270,392314,392272,392325,392273,392329,392317,392326,392332,392333,392335,392313,392319,392328,392323,392262,392320,392316,392271,432460,392331,392266,432542,392268,392274,392275,392327,392321,392334,392322,392315,432333,432589,392312,432449,432642,435503,432353,432668,435523,432523,432251,432652,432688,432320,432694,435520)) and (`webmarco`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}