SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 8312 
  AND combination_hash = '3241034084'

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
8312 sol-pp2-040-175 3241034084 436_11836 0.00 N 0 72.28 25000.00 1 0 9.54 0 0