On Insert 'Lock wait timeout exceeded; try restarting transaction'

Im getting below error while creating a document in custom doctype

Traceback (most recent call last):
File “/home/frappe/frappe-bench/apps/lms/lms/lms/doctype/cart/cart.py”, line 130, in create_loan_application
).insert(ignore_permissions=True)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py”, line 233, in insert
self.set_new_name(set_name=set_name, set_child_names=set_child_names)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py”, line 423, in set_new_name
set_new_name(self)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/naming.py”, line 49, in set_new_name
set_name_from_naming_options(autoname, doc)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/naming.py”, line 86, in set_name_from_naming_options
doc.name = make_autoname(autoname, doc=doc)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/naming.py”, line 143, in make_autoname
n = parse_naming_series(parts, doctype, doc)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/naming.py”, line 158, in parse_naming_series
part = getseries(n, digits)
File “/home/frappe/frappe-bench/apps/frappe/frappe/model/naming.py”, line 188, in getseries
current = frappe.db.sql(“SELECT current FROM tabSeries WHERE name=%s FOR UPDATE”, (key,))
File “/home/frappe/frappe-bench/apps/frappe/frappe/database/database.py”, line 146, in sql
self._cursor.execute(query, values)
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/cursors.py”, line 148, in execute
result = self._query(query)
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/cursors.py”, line 310, in _query
conn.query(q)
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/connections.py”, line 548, in query
self._affected_rows = self._read_query_result(unbuffered=unbuffered)
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/connections.py”, line 775, in _read_query_result
result.read()
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/connections.py”, line 1156, in read
first_packet = self.connection._read_packet()
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/connections.py”, line 725, in _read_packet
packet.raise_for_error()
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/protocol.py”, line 221, in raise_for_error
err.raise_mysql_exception(self._data)
File “/home/frappe/frappe-bench/env/lib/python3.6/site-packages/pymysql/err.py”, line 143, in raise_mysql_exception
raise errorclass(errno, errval)
pymysql.err.OperationalError: (1205, ‘Lock wait timeout exceeded; try restarting transaction’)