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 (
    10071, 10067, 10051, 10060, 10055, 10043, 
    10068, 10065, 10061, 10050, 10056, 
    10044, 10069, 10066, 12671, 12672, 
    15779, 12673, 12674, 12675, 12676, 
    12677, 12678, 12679, 9687, 10024, 10025, 
    10026, 10027, 10028, 10029, 10030
  ) 
  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 0.00072

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 (10071,10067,10051,10060,10055,10043,10068,10065,10061,10050,10056,10044,10069,10066,12671,12672,15779,12673,12674,12675,12676,12677,12678,12679,9687,10024,10025,10026,10027,10028,10029,10030)",
      "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}

Result

product_id price
9687 4000.00000000
10024 1716.01000000
10025 1716.01000000
10026 1716.01000000
10027 1716.01000000
10028 1716.01000000
10029 1716.01000000
10030 1716.01000000
10043 1929.60000000
10044 1929.60000000
10050 1929.60000000
10051 1929.60000000
10055 1929.60000000
10056 1929.60000000
10060 1929.60000000
10061 1929.60000000
10065 1929.60000000
10066 1929.60000000
10067 1929.60000000
10068 1929.60000000
10069 1929.60000000
10071 1929.60000000
12671 921.36000000
12672 921.36000000
12673 921.36000000
12674 921.36000000
12675 921.36000000
12676 921.36000000
12677 921.36000000
12678 921.36000000
12679 921.36000000
15779 921.36000000