SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 9457 
  AND combination_hash = '1406493483'

Query time 0.00028

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
9457 ATR-AAY-B1500-C2A 1406493483 1000_19636 3.00 N 0 642.60 24.00 0 0 0 0 117