SELECT 
  MIN(price) as min_price, 
  MAX(price) as max_price 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 434 
  AND price > 0 
GROUP BY 
  product_id

Query time 0.00036

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_options_inventory ref pc pc 3 const 11 Using where

Result

min_price max_price
5.52 82.74