Indexes are not being used even after enabling

gremlin> g.V().has('_id', '66b0dc9f2bd5e4709894fc29').profile()
==>Traversal Metrics
Step                                                               Count  Traversers       Time (ms)    % Dur
=============================================================================================================
JanusGraphStep([],[_id.eq(66b0dc9f2bd5e4709894f...                     1           1         101.875   100.00
  constructGraphCentricQuery                                                                   0.103
  constructGraphCentricQuery                                                                   0.017
  GraphCentricQuery                                                                          101.534
    \_condition=(_id = 66b0dc9f2bd5e4709894fc29)
    \_orders=[]
    \_isFitted=false
    \_isOrdered=true
    \_query=[]
    scan                                                                                     101.341
      \_query=[]
      \_fullscan=true
      \_condition=VERTEX
                                            >TOTAL                     -           -         101.875        -