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 (
    435351, 456510, 404001, 413818, 442117, 
    433550, 450230, 439049, 414690, 448070, 
    414544, 431904, 404473, 422990, 448236, 
    413068, 425901, 407405, 406178, 437072, 
    430766, 447574, 460572, 460325
  ) 
  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 0.00136

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.099614043,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_prices",
          "access_type": "range",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "key": "usergroup",
          "key_length": "9",
          "used_key_parts": ["product_id", "usergroup_id", "lower_limit"],
          "loops": 1,
          "rows": 48,
          "cost": 0.08425304,
          "filtered": 50,
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.product_id in (435351,456510,404001,413818,442117,433550,450230,439049,414690,448070,414544,431904,404473,422990,448236,413068,425901,407405,406178,437072,430766,447574,460572,460325) and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}