SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3968c7f997cefe1d0a4de359272269527f248f3c82f0909e684a341edb95994f' 
  AND token = 'oZiqJD28jN5qgVLjyX5wMGRmBbgrSmolHusPwPQn2Wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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