SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '564934d79aff5f4d4533fc081b246363fc050b0f00a0af6931a0800e0e3ae0c8' 
  AND token = 'vNHmODuFKHoIKLgjj+pxge3yeuUVFXj+xXDLZDqL6hA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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