SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65d1cf83b763499613b0563f82cac740d258246d0c1fb034512a1989b193d353' 
  AND token = '5RAgVTgXhxaopKLfm59BwXxJjg5sVGpKK2hQS++Kqik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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