We are already running into scams regarding this game.
Here's some quick information:
There are no keys or invites.
It's an account whitelist which means you need access to the seller's email, username and password to log into the account.
Beta invites will be around 100,000 and consistently expand over coming weeks according to leaks.
Do not fall for the scams or your own poor judgment when beta access restrictions will be eased soon.
The same happened to Riot's previous game Legends of Runeterra.
If you want to get into the beta head over to beta.playvalorant.com