SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 434 
  AND combination_hash = '501857739'

Query time 0.00048

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
434 eps-fas-sil-20 501857739 329_7558 0.00 N 0 5.52 5.00 1 0 15 0 10