SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 10946 
  AND combination_hash = '742062839'

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
10946 ODV-EDG-CK04-1000 742062839 1312_23887_1313_23900 0.00 N 2 525.20 19.00 0 0 0 0 10