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 (
    415288, 269868, 269870, 265423, 265427, 
    265433, 265422, 265411, 270140, 269842, 
    269869, 269838, 265431, 269871, 269853, 
    269845, 269872, 269860, 269867, 265430, 
    265412, 269843, 269835, 265403, 265414, 
    270143, 269840, 265419, 265413, 265424, 
    269848, 392318, 269851, 270139, 269863, 
    269837, 269865, 270155, 270141, 392269, 
    270142, 270144, 265428, 265408, 392330, 
    265401, 265420, 392264, 265465, 392324, 
    392270, 392272, 392314, 392325, 392273, 
    392329, 392317, 392326, 392332, 392333, 
    392335, 392313, 392319, 392320, 392328, 
    392262, 392323, 392316, 392271, 392331, 
    392266, 392268, 392274, 392275, 392327, 
    392321, 392334, 392315, 392322, 392312
  ) 
  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 0.00280

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "224.25"
    },
    "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": 160,
        "rows_produced_per_join": 160,
        "filtered": "100.00",
        "cost_info": {
          "read_cost": "192.25",
          "eval_cost": "32.00",
          "prefix_cost": "224.25",
          "data_read_per_join": "10K"
        },
        "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 (415288,269868,269870,265423,265427,265433,265422,265411,270140,269842,269869,269838,265431,269871,269853,269845,269872,269860,269867,265430,265412,269843,269835,265403,265414,270143,269840,265419,265413,265424,269848,392318,269851,270139,269863,269837,269865,270155,270141,392269,270142,270144,265428,265408,392330,265401,265420,392264,265465,392324,392270,392272,392314,392325,392273,392329,392317,392326,392332,392333,392335,392313,392319,392320,392328,392262,392323,392316,392271,392331,392266,392268,392274,392275,392327,392321,392334,392315,392322,392312)) and (`webmarco`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}