SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '868514ddd0f38828c9336995f59e1dc5a59873b91f6b8048642278460685ced4' 
  AND token = 'jlKqXBYtT7khHdiCar/EzwVRCMFOk4x95eOIOgCBN60=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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