Check for the actual string of a non-existent node token value in Drupal for auto_node_titles

if token equals literal token string value

<?php 
  $part = '[node:field_episode_part]'; // First we assign the tokenized value to a new PHP variable

  $partstring = '[node:' . 'field_episode_part]'; // Sometimes, especially when you are running a mass-update, you need to check for the literal string value, but you need to split it up in order for token to not intercept the value

  if((empty($part)) || ($part == $partstring)) { // Next, we check if that new variable is an empty string OR it equals the literal token string value
    return; // It is good form to return, even if your code returns no value. 
  } else { 
    return " (Part " . $part . ")"; // The formatted string that will be returned. 
  }
?>