This, and many more complex things, is possible thanks to regular expression syntax available in MySQL; you should use following clause:
WHERE field REGEXP 'abc-[a-zA-Z]$'
REGEXP is used here instead of LIKE to indicate MySQL that we are using here regular expression pattern, not 'ordinary' LIKE argument.
For more info about this topic see Appendix G:"Description of MySQL regular expression syntax " of MySQL manual.
Hope that helps.