Postgres Query running slow, using pgcrypto externsion in psotgres sql

using pgcrypto externsion in psotgres sql, following is the output for below queryies

Query 1:

explain analyze (select * from table_name);  

above query taking time around 900 ms

but when i am using query with 'pgp_sym_decrypt' it taking longer time around 54 sec, that is too high

Encrypted column is indexed

explain analyze (select
	pgp_sym_decrypt("table_name"."sender_contact_person_name",
	'encryption_key')::text,
	pgp_sym_decrypt("table_name"."sender_contact_person_email", 'encryption_key')::text,
	pgp_sym_decrypt("table_name"."sender_contact_person_contact_no",
	'encryption_key')::text,
	pgp_sym_decrypt("table_name"."recipient_contact_person_name",
	'encryption_key')::text,
	pgp_sym_decrypt("table_name"."recipient_contact_person_email",
	'encryption_key')::text,
	pgp_sym_decrypt("table_name"."recipient_contact_person_contact_no",
	'encryption_key')::text,
from
	"table_name"
where
	"table_name"."is_active"
order by
	"table_name"."pickup_date_time"
limit 10)