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 (
    14112, 14092, 14080, 14066, 14050, 14049, 
    14091, 14123, 14079, 14090, 14122, 
    14089, 14065, 14102, 14064, 14063, 
    14121, 14062, 14088, 14120, 14119, 
    14048, 14118, 14087
  ) 
  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 0.00065

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.06190128,
    "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": 0.04656984,
          "filtered": 49.95571136,
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.product_id in (14112,14092,14080,14066,14050,14049,14091,14123,14079,14090,14122,14089,14065,14102,14064,14063,14121,14062,14088,14120,14119,14048,14118,14087) and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}