SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 609 
  AND combination_hash = '913800764'

Query time 0.00031

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
609 MDM-15100 913800764 767_16435 0.00 N 100 3.32 0.20 75 0 75 0 5