MetaGraphs does not have indices - but then I am not so familiar with graph databases - so i don’t know if these even have indices.
I discovered that there are actually 2 Neo4j packages - not sure how well maintained they are at the monment:
There is GitHub - JuliaGraphs/GraphDataFrameBridge.jl: Tools for interoperability between DataFrame objects and LightGraphs and MetaGraphs objects, maybe it is easier to query a MetaGraph using the tools available for data frames.