Citing a map in MLA is the same as citing an image, graph, or chart (all are figures). Begin your figures with Fig. 1, then creator, then title or explanatory legend, then date.
When citing a Google Map, Google Map will be listed as the creator. The author will create the title or explanatory legend of the map. The date will be the date the map was accessed.
Fig 1. Google Maps, Country of Singapore, 14 June 2017.
Fig X. Creator, Title or explanatory legend, Date.
Use the "Web Image" option in Citefast to reference a map. Here is the reference for the map above:
Google Maps. Country of Singapore. Map. Google, 14 June 2017, goo.gl/maps/rV1wFku25eE2. Accessed 14 June 2017.
Creator. Title. Map or Chart. Site Title/Database, Date, URL. Dated Accessed.