How serious can this review invitation be? I published my first article a while ago, nothing special, just rigorous formalization of some well-known facts.

Now I got a mail writing


  We have read about your published precious paper in FORMALIZED MATHEMATICS titled About Quotient Orders and Ordering Sequences, and the topic of the paper has impressed us a lot.
  The paper has attracted attention from researchers and scholars specializing in quotient order; ordered finite sequences.


Especially the last part looks manufactured, that are just the keywords extracted.


  On behalf of the Editorial Board of the journal, we sincerely invite you to join our team as the editorial board member or reviewer of ******. Taking your academic background and rich experience in this field into account, the Board believe that you are quite qualified for this position. We believe that your position as the editorial board member or reviewer will shine a light on your research in related fields.


"academic background and rich experience" Yeah, but no. Really, really no, at this point in time.

So the email is clearly generated automatically, but the links seem to work and the journal does have entries in Google Scholar and an archive on their website, it is not a scam per se. It is an Open Access and Peer reviewed journal, but it is obvious I was just some entry and no one looked at my paper (or my academic background) seriously.

How serious can such an invitation be? Since it's a peer reviewed journal, are they just frantically looking for reviewers? Would they even consider a positive reaction of me, due to my academic short comings which start with me not even having a M.Sc. yet?

I'm specifically not asking for career advice. I'm not in the league of publication for too long, I don't really know how things like becoming a reviewer work, if this would be payed for anyhow, etc. If this mail constitutes a bad practice I would like to know because I will likely get more of these in the future.
Don't waste your time with it. You were smart to catch how the mail might have been generated (keywords etc). These mails are often sent out by journals that turn out to be predatory*; you wouldn't like to be associated with it.

If you accept, you may find your name being used here and there, in an attempt to increase the journal's scientific credibility. It is likely that their editorial board etc. is fluffed up in this manner (you could take a look at that if they've put up one, and see if there are any known researchers on their board). You are right — this is likely to happen repeatedly; ignore any requests that:


mention a specific paper of yours and extend editorial board invitations — it's a sign of auto-generated content.
appear in predatory journal lists.
have extremely general scope (eg. STEM) and no matching editorial board.




EDITS: 
(1)* Predatory journals,  in a nutshell, charge authors exorbitant fees to publish articles with little or no peer review, with very low visibility or scientific credibility. In the most extreme cases, the article may not even be published. In this manner, they are 'preying' on unsuspecting authors who submit their hard work. The linked question contains a detailed description.

(2) It would be a good idea not to respond to such mails at all, and to mark them as spam. Over time, it ll get easier to spot them right away.