SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '726ae41c997453e5e824a43391cc7383820bbc92acee026415f6c5c9a6eb1239' 
  AND token = 'yDkpWhTlpTQaFwi0/qFuY8aN/lT8uWydswyZYV971+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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