Here’s a calculation that works with any time difference.
For just hours and minutes, it would be:
{%- set word_for_and = 'and' %}
{%- set up_time = as_timestamp(utcnow())-as_timestamp(states.input_datetime.example.last_changed) %}
{%- macro phrase(name, plural_name, divisor, mod=None) %}
{%- set value = ((up_time // divisor) % (mod if mod else divisor)) | int %}
{%- set name = plural_name if value > 1 else name %}
{{- '{} {}'.format(value, name) if value | int > 0 else '' }}
{%- endmacro %}
{%- set values = [
phrase('hour', 'hours', 60*60),
phrase('minute', 'minutes', 60),
] | select('!=','') | list %}
{{ values[:-1] | join(', ') ~ ' ' ~ word_for_and ~ ' ' ~ values[-1] if values | length > 1 else values | first }}