That special API Key you mentioned is for OAuth, which is overkill for some app that accesses only your own account. Evernote has a developer token for that purpose.
Below is a simple example how you can get a note with title.
import evernote.edam.type.ttypes as Types
import evernote.edam.notestore.ttypes as NoteStore
from evernote.api.client import EvernoteClient
auth_token = "your developer token"
client = EvernoteClient(token=auth_token, sandbox=True)
note_store = client.get_note_store()
note_filter = NoteStore.NoteFilter()
note_filter.words = 'intitle:"test"'
notes_metadata_result_spec = NoteStore.NotesMetadataResultSpec()
notes_metadata_list = note_store.findNotesMetadata(note_filter, 0, 1, notes_metadata_result_spec)
note_guid = notes_metadata_list.notes[0].guid
note = note_store.getNote(note_guid, True, False, False, False)