SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18debeaa474b5ab52003826b48b304648ccd029300f679fc6d29caa16ec9d27b' 
  AND token = 'Qvnf/Roc9DTmzV18+UzfRvW0o0QhFf2AQHy+uyYAmjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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