For a single-value tuple, you need to use a check to modify the SQL query as well as how the tuple is passed. The single-value tuples will always have a comma at the end. You need to modify the query to be able to pass only the value from the tuple. The new query would look something like

query = ("""

select key,

case

 when column in {tuple1} then 1

 when column in ({tuple2}) then 2

end as check

from table

""".format(tuple1 = tuple1, tuple2 = tuple2[0], combo = combo))