search for a key within a inconsistent json file

Search a defined value at any path:

SELECT *
FROM users
WHERE JSON_SEARCH(data, 'one', 123);

Search a defined value at a defined path:

SELECT *
FROM users
WHERE JSON_SEARCH(data, 'one', 123) = '$.acctNum'; -- or '$.data.acctNum'

Search a defined property name and value at any path:

SELECT *
FROM users
WHERE JSON_SEARCH(data, 'all', 123) LIKE '%.acctNum"%';

fiddle