Asking the Editor-in-Chief about the reason of the review delay
In general, yes. The time for the review process varies between journals and between fields. you should, first of all try to assess what is normal for your field and particularly of the journal to which you submitted your work. 

For me as Editor-in-Chief of a journal in the Sciences, it seems long but not unheard of. I have had rare cases where I have had to chase reviewers for a paper and where I have had to wait about three weeks to dismiss anyone or to just get a negative response. All these requests add up. Add to that reviewers that do not return the review despite, even repeatedly, promising to do so. So, it could be a case of bad luck, but before you send off a polite request, check so that such time frames are not normal for the journal. In any case, do not assume that the problem is only with the editor. It could be but as mentioned can results from many steps in the review chain.

Regarding a template, just write a short and polite mail or letter asking what time frame you can expect. You can, for example, say that you wish to know so that you can free up time for your possible revisions or something to smooth the request. But a short question is never wrong as long as the time frame is obviously longer than common for the journal