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 (
    583, 1766, 2633, 1768, 2634, 605, 2218, 
    2105, 2101, 2106, 2712, 2102, 2103, 
    1456, 1397, 1398, 1499, 674, 675, 676
  ) 
  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 0.00101

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "14.91"
    },
    "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": 22,
        "rows_produced_per_join": 4,
        "filtered": "19.88",
        "index_condition": "(`zdrowy_db`.`cscart_product_prices`.`product_id` in (583,1766,2633,1768,2634,605,2218,2105,2101,2106,2712,2102,2103,1456,1397,1398,1499,674,675,676))",
        "cost_info": {
          "read_cost": "14.47",
          "eval_cost": "0.44",
          "prefix_cost": "14.91",
          "data_read_per_join": "104"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`zdrowy_db`.`cscart_product_prices`.`lower_limit` = 1) and (`zdrowy_db`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}

Result

product_id price
583 390.00000000
605 2.00000000
674 205.00000000
675 147.00000000
676 147.00000000
1397 117.00000000
1398 100.00000000
1456 69.85000000
1499 155.00000000
1766 1.80000000
1768 2.70000000
2101 2.40000000
2102 6.15000000
2103 7.50000000
2105 2.80000000
2106 3.60000000
2218 1.60000000
2633 2.51000000
2634 4.78000000
2712 3.72000000