Use name connectionStrings in app.config for Scaffold-DbContext EF 6 command

I've a "litle" problem to scaffold an existing database from SQL Server using Entity Framework 6 in my console app...

My connection string in App.config is:

<connectionStrings>
    <add name="connString"
         connectionString="Server=MyServer; Database=MyDb;User Id=MYUser ; Password=MyPW ; MultipleActiveResultSets=true;" 
         providerName="System.Data.SqlClient"/>
</connectionStrings> 

If I try to scaffold my database with this command:

Scaffold-DbContext -Connection name=connString Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Context MyDbContext -force

or

Scaffold-DbContext -Connection name=connectionString Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Context MyDbContext -force

or

Scaffold-DbContext "Name=connectionStrings:connString" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Context MyDbContext -force

The console always returns an error:

A named connection string was used, but the name '.......' was not found in the application's configuration. Note that named connection strings are only supported when using 'IConfiguration' and a service provider, such as in a typical ASP.NET Core application. See https://go.microsoft.com/fwlink/?linkid=850912 for more information.

So I tried to scaffold using plaintext connection string, and it didn't return any errors, but only the suggestion:

To protect potentially sensitive information in your connection string, you should move it out of source code. You can avoid scaffolding the connection string by using the Name= syntax to read it from configuration - see https://go.microsoft.com/fwlink/?linkid=2131148. For more guidance on storing connection strings, see http://go.microsoft.com/fwlink/?LinkId=723263.

So my question is:

What should I do to be able to write only the name of my connection string, rather than the connection string in clear text?

Thanks in advance