No one outside the company needs to be involved. In that process it may be wise to choose key-materials not creating allergic reactions. High security keys for high security complex. A professional locksmith knowing the key's profile and serial number. Will be able to make a new key without ever seen the lost one.
Padlocks can provide reasonable security in some situation.
Key handling is crucial, probably more important that the choice of key system. Some keys don't look like keys. Security manager Responsibilities Security Officers Responsibilities Make plans for who should have access to keys. Make rules where and how the keys should be stored and action taken if a key is missing. Identify doors suitable for key access.