SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 9852 
  AND combination_hash = '4238499760'

Query time 0.00027

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_options_inventory const PRIMARY,pc PRIMARY 4 const 1

Result

product_id product_code combination_hash combination amount temp position price weight min_qty max_qty qty_step list_qty_count aval_status
9852 5702328285491 4238499760 510_13248_523_13652 0.00 N 0 680.00 3.00 0 0 0 0 100