ohne DISTINCT
EXPLAIN

table           type    possible_keys   key   key_len  ref   rows  Extra
s_ticklist_ETR  range   zeit            zeit  4        NULL  5008  Using where

mit DISTINCT

EXPLAIN

table           type    possible_keys   key   key_len  ref   rows  Extra
s_ticklist_ETR  range   zeit            zeit  4        NULL  5008  Using where; Using temporary