add index to blocks' consensus

apps/explorer/priv/repo/migrations/20190301120328_add_index_to_consensus.exs

@@ -0,0 +1,7 @@
+defmodule Explorer.Repo.Migrations.AddIndexToConsensus do
+  use Ecto.Migration
+
+  def change do
+    create(index(:blocks, [:consensus]))
+  end
+end