SELECT 
  product_prices.product_id, 
  MIN(
    IF(
      product_prices.percentage_discount = 0, 
      product_prices.price, 
      product_prices.price - (
        product_prices.price * product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  product_prices 
WHERE 
  product_prices.product_id IN (
    218811, 218812, 218820, 243859, 218828, 
    218844, 218843, 218826, 218821, 242812, 
    276563, 276572, 218819, 218822, 218814, 
    218823, 219554, 259988, 219549, 222606, 
    224235, 219658, 225208, 225797, 226870, 
    218824, 218813, 219139, 218816, 218815
  ) 
  AND product_prices.lower_limit = 1 
  AND product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  product_prices.product_id

Query time 0.00265

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "24.92"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "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": 30,
        "rows_produced_per_join": 2,
        "filtered": "10.00",
        "index_condition": "(`goimagine`.`product_prices`.`product_id` in (218811,218812,218820,243859,218828,218844,218843,218826,218821,242812,276563,276572,218819,218822,218814,218823,219554,259988,219549,222606,224235,219658,225208,225797,226870,218824,218813,219139,218816,218815))",
        "cost_info": {
          "read_cost": "24.62",
          "eval_cost": "0.30",
          "prefix_cost": "24.92",
          "data_read_per_join": "71"
        },
        "used_columns": [
          "id",
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`goimagine`.`product_prices`.`lower_limit` = 1) and (`goimagine`.`product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}