I would like to have a simple solution (possibly in 1-3 plain API calls to AWS) to find the owner of an AWS access key. I have the password of the "root" AWS account and of course I can manage the users and credentials through IAM, but we have a lot of users and I don't want to look at them one by one looking for the owner of the key.

So basically I have a working access key + secret key pair (in fact a couple of them), but I do not know which user's key is it and what rights are on it. What is the easiest way to do this?

Thank you in advance.