i managed to restore zimbraAuthTokenLifetime value to original 12h without any improvment 
Code:
/opt/zimbra/openldap/bin/ldapmodify -h zimbra.xxxx.it -x -D "cn=config" -W
Enter LDAP Password:
dn: cn=default,cn=cos,cn=zimbra
changetype: modify
replace: zimbraAuthTokenLifetime
zimbraAuthTokenLifetime: 12h
modifying entry "cn=default,cn=cos,cn=zimbra"
/opt/zimbra/openldap/bin/ldapsearch -h zimbra.xxx.it -x -D "cn=config" -W |grep zimbraAuthTokenLifetime
Enter LDAP Password:
zimbraAuthTokenLifetime: 12h
[ 17:02:59 zimbra@zimbra ~/bin ]$ zmprov gac
ERROR: service.AUTH_EXPIRED (auth credentials have expired)