I have below table query which is executed to get the latest REG_LOG(table) update, perform full table scan to get the results.
WHERE REG_LOGGED_TIME > <last-access-time>
AND REG_LOGGED_TIME < '<current-time>'
AND REG_TENANT_ID = <tenant-id>
Have 2 fields in WHERE clause. There is first candidates for indexing. You should analyze selectivity of you fields. It is count distinct values divided by number rows. If result number is more then 200, you must create indexes.
CREATE INDEX ON REG_LOG (REG_TENANT_ID, REG_LOGGED_TIME);
Also you should review your other queries against this table. Probably you should create just one composite index. In this case, the first field must be column with biggest selectivity.