None of the following queries uses (or even considers) an index, despite there being an index that is a perfect match (e.g., on nt:unstructured with column "someProperty(STRING)"):

SELECT table.* FROM [nt:unstructured] AS table WHERE table.someProperty = $value
SELECT table.* FROM [nt:unstructured] AS table WHERE table.someProperty = 'literal'
SELECT * FROM [nt:unstructured] WHERE someProperty = $value

Interestingly, the following query does use the index:

SELECT * FROM [nt:unstructured] WHERE someProperty = 'literal'

So there appears to be a problem with properties on aliases and use of bind variables in constraints.