Way back when hotels commonly used this style of keys, I believe Yale, among others, made a keyhole blocker that had a cam not unlike the current Euro profile cylinders, and would fit in the keyhole and once the blocker’s key was turned to remove it, it effectively locked itself in the keyway. The standard key no longer would go in the keyhole. To open the door, you used the blocker’s key first to remove it completely, and then you used the standard key.
You might have luck finding one on eBay as I believe they are no longer made. I cannot guarantee that it will go into your lock, however.