There is an index index_services_on_type_and_id_and_template_when_active
introduced in 3a44d110 to optimize the queries performance for the
services usage data.

The usage data counter is iterating over the index in 10K batches,
without covering all the fields (type, id, template, instance), the
database would need to constantly look at the table for the instance
column (extra I/O).