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 (
    2474, 33695, 37944, 4808, 2744, 1064, 
    41370, 26867, 36295, 2158, 37307, 4872, 
    4806, 41356, 41373, 31945, 41369, 37299, 
    43461, 33698, 41366, 35690, 32307, 
    37292, 45569, 41402, 43842, 37281, 
    47622, 37286, 43841, 33700
  ) 
  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 0.00958

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 (2474,33695,37944,4808,2744,1064,41370,26867,36295,2158,37307,4872,4806,41356,41373,31945,41369,37299,43461,33698,41366,35690,32307,37292,45569,41402,43842,37281,47622,37286,43841,33700)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}