Actually, if you do a

select colname, index_keyseq from syscat.columns where tabname='BACKUPS'

you'll find that columns are indexed like so:

NODE_NAME                         1
FILESPACE_NAME                    2
STATE                             3
TYPE                              4
HL_NAME                           5
LL_NAME                           6

You can speed up the search significantly by specifying as many values as
you can.  Note, once you break the 123456 chain, specifying values below the
break doesn't speed the search any.

Note, if you want both active and inactive, two selects runs really fast,
and I think something like

... filespace_name='whatever' and (state='ACTIVE_VERSION or
state='INACTIVE_VERSION') and type='FILE' ...

would actually use the keys also and run just as fast.