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 (
    5032, 5028, 5030, 5029, 5036, 5461, 5458, 
    5328, 5047, 5365, 5033, 5456, 5596, 
    5367, 5500, 5054, 5335, 5504, 5506, 
    5464, 5508, 6081, 6144, 6083, 6189, 
    6145, 5644, 6297, 6190, 6276, 6303, 
    6260, 6305, 6274, 6301, 6824, 6825
  ) 
  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 0.00138

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "25.91"
    },
    "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": 37,
        "rows_produced_per_join": 7,
        "filtered": "19.99",
        "index_condition": "(`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`product_id` in (5032,5028,5030,5029,5036,5461,5458,5328,5047,5365,5033,5456,5596,5367,5500,5054,5335,5504,5506,5464,5508,6081,6144,6083,6189,6145,5644,6297,6190,6276,6303,6260,6305,6274,6301,6824,6825))",
        "cost_info": {
          "read_cost": "25.17",
          "eval_cost": "0.74",
          "prefix_cost": "25.91",
          "data_read_per_join": "177"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`lower_limit` = 1) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}