Been asked to peer review, unsure as to qualifications? I have been asked to peer review a paper related to my field of expertise. My educational level is MSc, however I am published. I am referred to as Doctor throughout the request email even though when published, this is not how I refer to myself by any means. This has occurred before and I responded that whilst I would be willing to peer review, I was not a PhD, however they asked me to do it regardless (a different journal than the current requesting journal). I am willing to peer review again and am extremely thorough and capable of doing so, however I don’t think you could call me an expert in terms of years and years of papers and academia. I am not sure how to respond. Firstly how was I chosen, was it random or specific enough; it’s a wide field and even when honest about qualifications I was asked to go ahead. Anyone have any thoughts?

Just to add this is a journal under the same umbrella group that I previously reviewed for and one in all likelihood I will submit to myself in the future. Would refusing a request for per review then go against me?
Assuming this is a reputable journal, then I don't see any problem, especially if the manuscript is in your areas of expertise.   It is this expertise the editor seeks.  It is not how long you have been in academia.  A good editor will seek multiple opinions.  Since you have published in the same area, then you are in a good position to provide useful opinions.

Editors usually do a Google search to find people who have published in the same area.  Alternatively, the manuscript in question may have cited your past works.  Also, editors tend to have their personal pool of reviewers.  Any papers assigned to them will then go these reviewers. Lastly, the journal submission system may maintain a pool of reviewers or past authors and their expertise.