serch_word = '茶'
utftext =  serch_word.encode('utf-8')
urlencode = urllib.parse.quote(utftext, '')
result = mastodon.search('https://mstdn.jp/api/v1/search?q=' + urlencode)
print(result)

{'hashtags': [], 'accounts': [], 'statuses': []}

https://${MASTODON_HOST}/api/v1/search?q=${keyword}