standalone-backbase.xml

...
<subsystem xmlns="urn:jboss:domain:datasources:2.0">
    <datasources>
        <datasource jndi-name="java:jboss/datasources/MySQLDataSource" pool-name="MySQLDataSourcePool" enabled="true" use-java-context="true">
            <connection-url>jdbc:mysql://localhost/test</connection-url>
            <driver>mysql</driver>
        </datasource>
        <drivers>
            <driver name="mysql" module="com.mysql">
                <datasource-class>com.mysql.jdbc.Driver</datasource-class>
            </driver>
        </drivers>
    </datasources>
</subsystem>
...