Although a review has been published as a "systematic review", it may not conform to the systematic review protocol and be demonstrably rigorous, reproducible or exhaustive. There are a number of criteria by which you can assess the quality of a systematic review. Below are some tools used for this purpose.
The MMAT is a critical appraisal tool that was developed for use in systematic mixed studies reviews (i.e., reviews combining qualitative, quantitative and/or mixed methods studies).