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 (
    47592, 5478, 6371, 47652, 1751, 461, 
    5960, 5957, 34548, 5999, 5961, 4363, 
    5956, 4361, 5451, 46696, 5479, 4366, 
    4360, 1752, 5485, 47610, 41410, 41010, 
    5963, 41411, 5447, 4365, 47605, 48279, 
    47606, 5469
  ) 
  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 0.00148

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 (47592,5478,6371,47652,1751,461,5960,5957,34548,5999,5961,4363,5956,4361,5451,46696,5479,4366,4360,1752,5485,47610,41410,41010,5963,41411,5447,4365,47605,48279,47606,5469)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}