SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b256a5dbcae5ada54b1dc43329b5168b98523c36a82395b050baac2591697b1d' 
  AND token = 'bM9NQnP2jOOlEOoQeBeIPEzwgxw1IrYGiL3sZW+NZ+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables