DROP TABLE IF EXISTS test_json_index;
CREATE TABLE test_json_index
(
	id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
	OrgID INT NOT NULL,
	DataBlob json NOT NULL
);
ALTER TABLE test_json_index
ADD INDEX (OrgID),
ADD INDEX indexA (( CAST(DataBlob->'$.a' AS UNSIGNED INTEGER ARRAY) )),
ADD INDEX indexB (( CAST(DataBlob->'$.b' AS UNSIGNED ) ));

INSERT INTO test_json_index (OrgID, DataBlob)
VALUES(
1, "{\"a\":[1, 2, 3], \"b\": 1}"
);
INSERT INTO test_json_index (OrgID, DataBlob)
VALUES(
2, "{\"a\":[4, 5, 6], \"b\": 2}"
);

SHOW INDEX FROM test_json_index;

EXPLAIN SELECT *
FROM (SELECT * from test_json_index where OrgID = 1) as tmp
WHERE 1 member of(tmp.DataBlob->'$.a');

EXPLAIN SELECT *
FROM test_json_index
WHERE 1 member of(DataBlob->'$.a') AND OrgID = 1;

EXPLAIN SELECT *
FROM (SELECT * from test_json_index where OrgID = 1) as tmp
WHERE 1 = CAST(DataBlob->'$.b' AS UNSIGNED);

EXPLAIN SELECT *
FROM test_json_index
WHERE 1 = CAST(DataBlob->'$.b' AS UNSIGNED) AND OrgID = 1;