How to create filter rule in Gmail that marks certain spam messages as read?

Question

In Gmail, this search produces the desired results: in:anywhere from:(onmicrosoft.com) mcafee.

I see plenty of unread spam.

I want to create a filter rule with that query and tell Gmail to either delete those spam messages automatically or at least mark them as read. I don't want to see any of those spam messages as counted in the unread spam counter.

But when I click Create Filter, a modal then says:

Filter searches containing "label:", "in:", "is:", date range (e.g. "before:" or "after:") or stars criteria (e.g. "has:yellow-star") are not recommended as they will never match incoming mail. Do you still wish to continue to the next step?

When I accept, it automatically converts my query to from:(onmicrosoft.com) label:ast mcafee which then does not produce the desired results.

How can I achieve my goal?

P.S. Less important but I'm also curious: What does label:ast mean?

Answer 1

I will accept an answer that offers more explanation, but I just noticed that when I created this other variation: from:(onmicrosoft.com) is:spam mcafee it then converted to from:(onmicrosoft.com) label:spam mcafee, and that version seems to work.

https://webapps.stackexchange.com/a/5037/27487 was helpful.