How to compare current time with a time variable in MySQL

I need to write a query in which I should compare current time with a variable which contains some time.

SQL Query:

select time >= curtime() from appointment;

Here time is the variable which has some time.

This is the error I'm getting:

Illegal mix of collations (utf8_general_ci,IMPLICIT) and (latin1_swedish_ci,NUMERIC) for operation '>='; nested exception is java.sql.SQLException: Illegal mix of collations (utf8_general_ci,IMPLICIT) and (latin1_swedish_ci,NUMERIC) for operation '>='

I've already tried using time(now()) but it doesn't work.