the path should be:
/core/components/mycomponent/migxconfigs/mymigxconfig.config.inc.php
You should have the packagename defined in your MIGX-configuration
Than you can export your configuration with 'export to package'
After Installation of your package you can import this configuration into the MIGX-Configurator with 'import from package'
If don't want to import your config, you can use this exported json-file directly by adding the packagename to the configs-property
In TV-input-options:
configs: mymigxconfig:mycomponent
for the CMP-action, if you've created a CMP: &configs=mymigxconfig:mycomponent