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 (
    3196, 33703, 37282, 40759, 33701, 37885, 
    2151, 6045, 40811, 5642, 2472, 47604, 
    6363, 15613, 2473, 3991, 3465, 5643, 
    4823, 37295, 5772, 2565, 37298, 1850, 
    2155, 47592, 2626, 26862, 41130, 37280, 
    21746, 37881
  ) 
  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 0.00331

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 (3196,33703,37282,40759,33701,37885,2151,6045,40811,5642,2472,47604,6363,15613,2473,3991,3465,5643,4823,37295,5772,2565,37298,1850,2155,47592,2626,26862,41130,37280,21746,37881)",
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    ]
  }
}