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 (
    10793, 10794, 10795, 10796, 10797, 10798, 
    10799, 10800, 10801, 10802, 10803, 
    10804, 10805, 10806, 10807, 10808, 
    10809, 10810, 10811, 10812, 10827, 
    10828, 9686, 10767, 10768, 10769, 10770, 
    10771, 10772, 10773, 10774, 10775
  ) 
  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 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "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": 99.23484039,
      "index_condition": "cscart_product_prices.product_id in (10793,10794,10795,10796,10797,10798,10799,10800,10801,10802,10803,10804,10805,10806,10807,10808,10809,10810,10811,10812,10827,10828,9686,10767,10768,10769,10770,10771,10772,10773,10774,10775)",
      "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}

Result

product_id price
9686 4000.00000000
10767 5972.60000000
10768 5972.60000000
10769 5972.60000000
10770 5972.60000000
10771 5972.60000000
10772 5972.60000000
10773 5972.60000000
10774 5972.60000000
10775 5972.60000000
10793 1582.30000000
10794 1582.30000000
10795 1582.30000000
10796 1582.30000000
10797 1582.30000000
10798 1582.30000000
10799 1582.30000000
10800 1582.30000000
10801 1582.30000000
10802 1582.30000000
10803 1582.30000000
10804 1582.30000000
10805 1582.30000000
10806 1582.30000000
10807 1582.30000000
10808 1582.30000000
10809 1582.30000000
10810 1582.30000000
10811 1582.30000000
10812 1582.30000000
10827 1582.30000000
10828 1582.30000000