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 (
    41130, 1306, 6660, 1305, 4785, 37881, 
    4795, 41124, 4789, 20830, 6647, 6650, 
    41423, 41134, 4787, 4793, 41102, 41428, 
    2162, 41424, 1840, 4803, 36496, 41138, 
    41427, 4801, 4799, 2625, 4797, 37895, 
    41426, 19195
  ) 
  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 0.00199

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 (41130,1306,6660,1305,4785,37881,4795,41124,4789,20830,6647,6650,41423,41134,4787,4793,41102,41428,2162,41424,1840,4803,36496,41138,41427,4801,4799,2625,4797,37895,41426,19195)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}