Airtable has not published information this granular on the rate limit. However, I doubt that you can get more requests per second by using multiple access tokens for the same user account.
There also is a potential for the rate limit to be somehow linked to the workspace or base. So, it might be the case that you might need to take into account all the APIs calls across users for a particular workspace, but not calls for the same access token in a different workspace. You also need to take into account OAUTH API calls.
I don't expect to get a clear answer from Airtable that granular, and it might change. But I also think that it probably doesn't matter. If you need significantly higher rate limits, Airtable might not be the right platform for you.
with the API keys we have several people who assigned API key - this works so no rate limit for the base. But there can only be 1 API key per person. With the personal access tokens there can be multiple. I will look for the Airtable support page to see if I can submit a ticket asking them directly.
I am disappointed there is no Airtable response to this question so I am going on basis that personal access token will work same as API key
😥