@Maik and @Luis_W__Flor_Go
While we still have the R80 CCSM exam available (until 31 March) you qualify to sit that exam to get the CCSM. Your R80 CCSE does not have to be current to take that exam.
Getting an extension requires you to have a valid CCSE and in the New model you will only be able to reach CCSM with a valid CCSE.
The same applies to the R80 CCSE Update exam. While it is available, you may recertify the CCSE with that exam even if your CCSE is expired. After 31 March, you will have to recertify using the regular R80 CCSE exam (156-315.80).
Hope this helps.