SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '284d921652a2c40bebe237bf111e6476efd011011992e4b9351072b92ba459bc' 
  AND token = '1VXTKl+ZTgPy3zmCKWhXw++dxMEuO2qNHhsO7CgIHJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}