Import a single yml configuration file
You can use 

$ drush cim --partial --source=only-few-configs/


Your help says:

$ drush cim --help
Import config from a config directory.

Examples:
 drush config-import --partial             Import configuration; do not remove missing configuration.

Arguments:
 label                                     A config directory label (i.e. a key in $config_directories array in 
                                           settings.php). Defaults to 'sync'

Options:
 --partial                                 Allows for partial config imports from the source directory. Only updates and new 
                                           configs will be processed with this flag (missing configs will not be deleted).   
 --preview=&lt;list&gt;                          Format for displaying proposed changes. Recognized values: list, diff. Defaults   
                                           to list.                                                                          
 --source                                  An arbitrary directory that holds the configuration files. An alternative to      
                                           label argument

Aliases: cim