This cannot be done directly in the current implementation of the database. However, this search can be done in several steps by 1) querying all the events mentioned in the first catalog; 2) querying all the events mentioned in the first and second catalogs simultaneously; 3) subtracting the results of the second query from the results of the first query.
Sorry, we do not currently provide such an option.
Based on personal experience, we suggest that users expand the IRIS FOV by 100 arcsecs. Positions of the GOES flares are often determined based on the active regions, and use of a smaller expansion may result in loss of some events of interest during the query.