SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 479 
  AND combination_hash = '3299239303'

Query time 0.00025

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
479 ODV-SML-CK02-0000S 3299239303 860_17679 0.00 N 0 1729.27 26.00 0 0 0 0 126