Griffiths Valuation for this area is virtually contemporary with the period when Matthew Keown gave up the license for the Belfast Hotel.
If you search for all residents in Whiteabbey village (search for 'white abbey', ie. with a space between the words) you will see Matthew Keown with several properties together (references 77 / 78 / 79) which the valuation would indicate are more substantial than surrounding properties - part or all of these are likely to be the Belfast Hotel.
There are two Boyds listed, a John (reference 60) living in a seemingly ordinary house and an Andrew Boyd in a more substantial property which is the very next entry (reference 80) to the Matthew Keown listing. This initially seemed like too much of a coincidence, however when I glanced at the (quite long) will for Andrew Boyd of Whiteabbey (he only died a few years later) I could see nothing to tie it in to the whole Martha Carson / Victoria Boyd story - go look at it yourself on the PRONI website.
So the proximity of Andrew Boyd might be co-incidental after all. Boyd is a common enough surname in the wider Carnmoney parish area...