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 (
    12, 17, 148, 180, 187, 232, 230, 231, 18, 
    16, 4, 5, 23, 24, 170, 1, 22, 149, 227, 
    78, 79, 190, 189, 286, 287, 162, 159, 
    158, 245, 238, 239, 242
  ) 
  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 0.00087

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "118.39"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "64.00"
      },
      "table": {
        "table_name": "cscart_product_prices",
        "access_type": "ALL",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "rows_examined_per_scan": 256,
        "rows_produced_per_join": 64,
        "filtered": "25.00",
        "cost_info": {
          "read_cost": "41.59",
          "eval_cost": "12.80",
          "prefix_cost": "54.39",
          "data_read_per_join": "1K"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`rajansecarter_15_june_mve`.`cscart_product_prices`.`lower_limit` = 1) and (`rajansecarter_15_june_mve`.`cscart_product_prices`.`product_id` in (12,17,148,180,187,232,230,231,18,16,4,5,23,24,170,1,22,149,227,78,79,190,189,286,287,162,159,158,245,238,239,242)) and (`rajansecarter_15_june_mve`.`cscart_product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}