SELECT 
  cscart_aprilproduct_prices.product_id, 
  MIN(
    IF(
      cscart_aprilproduct_prices.percentage_discount = 0, 
      cscart_aprilproduct_prices.price, 
      cscart_aprilproduct_prices.price - (
        cscart_aprilproduct_prices.price * cscart_aprilproduct_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_aprilproduct_prices 
WHERE 
  cscart_aprilproduct_prices.product_id IN (
    159, 158, 245, 238, 239, 242, 243, 241, 
    240, 214, 217, 218, 207, 59, 58, 60, 199, 
    198, 94, 96, 201, 114, 192, 136
  ) 
  AND cscart_aprilproduct_prices.lower_limit = 1 
  AND cscart_aprilproduct_prices.usergroup_id IN (0, 1) 
GROUP BY 
  cscart_aprilproduct_prices.product_id

Query time 0.00078

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "101.98"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "48.00"
      },
      "table": {
        "table_name": "cscart_aprilproduct_prices",
        "access_type": "ALL",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "rows_examined_per_scan": 254,
        "rows_produced_per_join": 47,
        "filtered": "18.90",
        "cost_info": {
          "read_cost": "44.38",
          "eval_cost": "9.60",
          "prefix_cost": "53.98",
          "data_read_per_join": "1K"
        },
        "used_columns": [
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`vishalecarter_april_setup`.`cscart_aprilproduct_prices`.`lower_limit` = 1) and (`vishalecarter_april_setup`.`cscart_aprilproduct_prices`.`product_id` in (159,158,245,238,239,242,243,241,240,214,217,218,207,59,58,60,199,198,94,96,201,114,192,136)) and (`vishalecarter_april_setup`.`cscart_aprilproduct_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}