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 (
    4365, 5768, 41426, 1050, 36493, 2252, 
    47606, 5469, 3988, 4468, 36297, 2249, 
    5464, 5474, 41438, 353, 33721, 33714, 
    3997, 41008, 2260, 41018, 1753, 43649, 
    44273, 41009, 3999, 41230, 4364, 36270, 
    28158, 27077
  ) 
  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 0.00683

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_prices",
          "access_type": "range",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "key": "product_id",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "rows": 32,
          "filtered": 99.9960556,
          "index_condition": "cscart_product_prices.product_id in (4365,5768,41426,1050,36493,2252,47606,5469,3988,4468,36297,2249,5464,5474,41438,353,33721,33714,3997,41008,2260,41018,1753,43649,44273,41009,3999,41230,4364,36270,28158,27077)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}