Iterate over a dict except for x item items

I have a dict in this format:

d_data = {'key_1':value_1,'key_2':value_2,'key_3':value_3,'key_x':value_x,'key_n':value_n}

and I have to iterate over it's items:

for key,value in columns.items():
    do something

except for the pair:

'key_x':value_x