That seems to be an EPEL package. Maybe you need to run
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 if you have the epel-release package installed. If you don't, maybe
rpm --import http://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-7 works better. In normal circumstances yum will ask you to import the key the first time you try to use an EPEL package, but perhaps your situation is different.