SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cf61eed4f83b3df8b5cb99203b49bec7da5c52b3747d57a56f9187b6471d215' 
  AND token = 'WZDd/nALLXbaC/GslunQUv5qNjX1MsrZp2TgUaTBnk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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