do you have any performance benchmark numbers for this one or is this more speculative?

Yeah, it's kinda of speculative but I can get some data

For the above queries, with db

SELECT COUNT(*) FROM TokenIndexEntity;
74942 rows

SELECT COUNT(*) FROM TokenIndexEntity WHERE resourceType = 'Location';
11784 rows

SELECT COUNT(*) FROM ResourceEntity;
8881 rows

SELECT COUNT(*) FROM ResourceEntity WHERE resourceType = 'Location';
1966 rows

The first query took around 17ms and the second one 7ms

Additional context

SELECT COUNT(*)
FROM (SELECT resourceUuid
      FROM TokenIndexEntity
      WHERE resourceType = 'Location'
        AND index_name = 'status'
        AND index_value = 'active'

      INTERSECT

      SELECT resourceUuid
      FROM TokenIndexEntity
      WHERE resourceType = 'Location'
        AND index_name = 'type'
        AND (index_value = 'bu' AND
             IFNULL(index_system, '') = 'http://terminology.hl7.org/CodeSystem/location-physical-type'));

57 rows

SELECT COUNT(*)
FROM (SELECT resourceUuid
      FROM TokenIndexEntity
      WHERE resourceType = 'Location'
        AND index_name = 'status'
        AND index_value = 'active'

      UNION ALL

      SELECT resourceUuid
      FROM TokenIndexEntity
      WHERE resourceType = 'Location'
        AND index_name = 'type'
        AND (index_value = 'bu' AND
             IFNULL(index_system, '') = 'http://terminology.hl7.org/CodeSystem/location-physical-type'));

2023 rows