You can get rid of the all_different and count constraints as follows:
T_1 in 0..59,
T_2 in 0..59,
...
T_n in 0..59,
Slot_0 in 0..1,
Slot_1 in 0..1,
...
Slot_59 in 0..1,
global_cardinality([T_1, T_2, ..., T_n], [0-Slot_0, 1-Slot_1, ..., 59-Slot_59]).