Custom-Post-Type – how can I get the only post by IDnumber?

You query is completely wrong and mingled. You are using WP_Query and get_post together and intermingled in one query, which will never work

To retrieve just one single post, make use of get_post. You can delete your complete query in your question. Replace it with something like this

<?php
   $post_64 = get_post(64); 
   echo $post_64->post_title;
?>