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 (
    692, 1189, 845, 765, 598, 1024, 1416, 
    1432, 1410, 558, 557, 556, 1421, 1406, 
    1422, 1413, 753, 566, 1021, 536, 686, 
    519, 764, 1226, 1419, 1447, 613, 545, 
    685, 1012
  ) 
  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 0.00134

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": 30,
      "filtered": 6.122447491,
      "index_condition": "cscart_product_prices.product_id in (692,1189,845,765,598,1024,1416,1432,1410,558,557,556,1421,1406,1422,1413,753,566,1021,536,686,519,764,1226,1419,1447,613,545,685,1012)",
      "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}