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 (
    4414, 4412, 4416, 7588, 7589, 7590, 7591, 
    7592, 7240, 7237, 7236, 7238, 7239, 
    5875, 5877, 5874, 5879, 5880, 5873, 
    5876, 5878, 5881, 5872, 3999, 4004, 
    4005, 4003, 4002, 4006, 4001, 4000, 
    4598, 2510, 2507, 2508, 2511, 2509, 
    3753, 489, 493, 494, 488, 492, 416, 497, 
    495, 3182, 3181
  ) 
  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 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "33.61"
    },
    "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": 48,
        "rows_produced_per_join": 9,
        "filtered": "19.12",
        "index_condition": "(`dbggbern`.`cscart_product_prices`.`product_id` in (4414,4412,4416,7588,7589,7590,7591,7592,7240,7237,7236,7238,7239,5875,5877,5874,5879,5880,5873,5876,5878,5881,5872,3999,4004,4005,4003,4002,4006,4001,4000,4598,2510,2507,2508,2511,2509,3753,489,493,494,488,492,416,497,495,3182,3181))",
        "cost_info": {
          "read_cost": "32.69",
          "eval_cost": "0.92",
          "prefix_cost": "33.61",
          "data_read_per_join": "220"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`dbggbern`.`cscart_product_prices`.`lower_limit` = 1) and (`dbggbern`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}