SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 10705 
  AND combination_hash = '3714299116'

Query time 0.00039

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
10705 87LS01 882M01 3714299116 1295_23687_1293_23673 20.00 N 0 950.30 44.00 0 0 0 0 1