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 (
    25180, 4071, 3004, 294, 4515, 5581, 47603, 
    48844, 6367, 4500, 4269, 4270, 6557, 
    3669, 1750, 1041, 35188, 25850, 4073, 
    46715, 35859, 2457, 3975, 2257, 2019, 
    4070, 4263, 46749, 47278, 39612, 18748, 
    788
  ) 
  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 0.15192

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_product_prices.product_id",
      "temporary_table": {
        "nested_loop": [
          {
            "table": {
              "table_name": "cscart_product_prices",
              "access_type": "ref",
              "possible_keys": [
                "usergroup",
                "product_id",
                "lower_limit",
                "usergroup_id"
              ],
              "key": "lower_limit",
              "key_length": "3",
              "used_key_parts": ["lower_limit"],
              "ref": ["const"],
              "rows": 25327,
              "filtered": 8.333330154,
              "attached_condition": "cscart_product_prices.lower_limit <=> 1 and cscart_product_prices.product_id in (25180,4071,3004,294,4515,5581,47603,48844,6367,4500,4269,4270,6557,3669,1750,1041,35188,25850,4073,46715,35859,2457,3975,2257,2019,4070,4263,46749,47278,39612,18748,788) and cscart_product_prices.usergroup_id in (0,1)"
            }
          }
        ]
      }
    }
  }
}