SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0e53dbbc8d217d02aecbdcfda44e75ed8fb6ffddb631807d5bf6d43e52f5383' 
  AND token = 'YET5x1wD0hxAe6lU6Ng5xsAbGd9XhWbjduf/ye5pTmk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

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