Just call it a Licenciatura and indicate in parentheses that it is a five-year undergraduate course of study. For example you might say (obviously adjusting to the format of your C.V.)
2004 - Licenciatura en sociología (5 year undergraduate degree in sociology), Complutense University of Madrid.
2004 - Lic. Sociología (equiv. B.S./B.A. Sociology), Complutense University of Madrid.
The reason I'd recommend not translating it as a masters is that the licenciatura not considered a graduate level program (you could homologar 4-year undergraduate U.S. bachelor programs into licenciaturas back in the day), and seeing the abbreviation M.A./M.S. would imply that it is graduate level. You can discuss it in a cover letter if you feel the need to explain it further.