SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cf5cf83ac4a51608d571e3bebfde3a8606344974c33e8baf8c56568d7d0061f' 
  AND token = 'VQ1WyR6tTnIWjR62vEB3EWOGAu9/X3BmQoAgJSl4X9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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