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 (
    9825, 9826, 9827, 9828, 9829, 9830, 15732, 
    9797, 9798, 9799, 9800, 9801, 9802, 
    9803, 9804, 9805, 9806, 9807, 9808, 
    9809, 9810, 9811, 9812, 9775, 9776, 
    9777, 9778, 9779, 9780, 9781, 9782, 
    9783
  ) 
  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 0.00504

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 (9825,9826,9827,9828,9829,9830,15732,9797,9798,9799,9800,9801,9802,9803,9804,9805,9806,9807,9808,9809,9810,9811,9812,9775,9776,9777,9778,9779,9780,9781,9782,9783)",
      "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}

Result

product_id price
9775 1292.58000000
9776 1292.58000000
9777 1292.58000000
9778 1292.58000000
9779 1292.58000000
9780 1292.58000000
9781 1292.58000000
9782 1292.58000000
9783 1292.58000000
9797 1292.58000000
9798 1292.58000000
9799 1292.58000000
9800 1292.58000000
9801 1292.58000000
9802 1292.58000000
9803 1292.58000000
9804 1292.58000000
9805 1292.58000000
9806 1292.58000000
9807 1292.58000000
9808 1292.58000000
9809 1292.58000000
9810 1292.58000000
9811 1292.58000000
9812 1292.58000000
9825 1136.58000000
9826 1136.58000000
9827 1136.58000000
9828 1136.58000000
9829 1136.58000000
9830 1136.58000000
15732 1136.58000000