SELECT 
  * 
FROM 
  cscart_product_options_inventory 
WHERE 
  product_id = 750 
  AND combination_hash = '3203569713'

Query time 0.00023

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
750 87CS01 89301 3203569713 1188_22396_1156_21888_1189_22398_1187_22389 14.00 N 0 1327.20 44.00 0 0 0 0 1