It is in the case if you just use just first in the predicate.
It will do scan if you use first columns of composite key and non-key column of composite key.
To trick it you can just dummy predicates like this and then non-key column:
[A,B] is your index, [C] - another column
To utilize index you write as:
SELECT A,B,C,D,E FROM test WHERE A=1 AND B=B AND C=3