Postgres 12

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CREATE TABLE tbl (
  id    uuid PRIMARY KEY
, data  json
, datab jsonb
);

INSERT INTO tbl VALUES
  ('4BF30FE6-D7DD-480B-8592-DC9676576FEF', '{"timestamps":{ "created":1578614541, "modified":1578615707 }, "type":"single"}', '{"timestamps":{ "created":1578614541, "modified":1578615707 }, "type":"single"}')
, ('1AC2CD8F-09D0-456C-9FD4-B63E354BD324', '{"timestamps":{ "created":1578614676, "modified":1578615921 }, "type":"multiple"}', '{"timestamps":{ "created":1578614676, "modified":1578615921 }, "type":"multiple"}')
, ('50AD2D82-5919-4555-BCC2-B24E0DE24263', '{"timestamps":{ "created":1578614552, "modified":1578615784 }, "type":"single"}', '{"timestamps":{ "created":1578614552, "modified":1578615784 }, "type":"single"}')
, ('8C3BE671-17D1-49FD-A891-D5E69FDF7FC2', '{"timestamps":{ "created":1578614685, "modified":1578615173 }, "type":"single"}', '{"timestamps":{ "created":1578614685, "modified":1578615173 }, "type":"single"}')
; 

CREATE INDEX tbl_data_created_idx ON tbl (((data #>> '{timestamps,created}')::int));
CREATE INDEX tbl_datab_created_idx ON tbl (((datab #>> '{timestamps,created}')::int));

CREATE TABLE

INSERT 0 4

CREATE INDEX

CREATE INDEX

SELECT id, data
FROM   tbl
WHERE (data #>> '{timestamps,created}')::int > 1578614670;

id
data

1ac2cd8f-09d0-456c-9fd4-b63e354bd324
{"timestamps":{ "created":1578614676, "modified":1578615921 }, "type":"multiple"}

8c3be671-17d1-49fd-a891-d5e69fdf7fc2
{"timestamps":{ "created":1578614685, "modified":1578615173 }, "type":"single"}

SELECT 2

SELECT id, datab
FROM   tbl
WHERE (datab #>> '{timestamps,created}')::int > 1578614670;

id
datab

1ac2cd8f-09d0-456c-9fd4-b63e354bd324
{"type": "multiple", "timestamps": {"created": 1578614676, "modified": 1578615921}}

8c3be671-17d1-49fd-a891-d5e69fdf7fc2
{"type": "single", "timestamps": {"created": 1578614685, "modified": 1578615173}}

SELECT 2

SELECT id, data
FROM   tbl
WHERE (data -> 'timestamps' ->> 'created')::numeric > 1578614670;

id
data

1ac2cd8f-09d0-456c-9fd4-b63e354bd324
{"timestamps":{ "created":1578614676, "modified":1578615921 }, "type":"multiple"}

8c3be671-17d1-49fd-a891-d5e69fdf7fc2
{"timestamps":{ "created":1578614685, "modified":1578615173 }, "type":"single"}

SELECT 2

SELECT id, datab
FROM   tbl
WHERE (datab -> 'timestamps' ->> 'created')::numeric > 1578614670;

id
datab

1ac2cd8f-09d0-456c-9fd4-b63e354bd324
{"type": "multiple", "timestamps": {"created": 1578614676, "modified": 1578615921}}

8c3be671-17d1-49fd-a891-d5e69fdf7fc2
{"type": "single", "timestamps": {"created": 1578614685, "modified": 1578615173}}

SELECT 2

id	data
1ac2cd8f-09d0-456c-9fd4-b63e354bd324	{"timestamps":{ "created":1578614676, "modified":1578615921 }, "type":"multiple"}
8c3be671-17d1-49fd-a891-d5e69fdf7fc2	{"timestamps":{ "created":1578614685, "modified":1578615173 }, "type":"single"}

id	datab
1ac2cd8f-09d0-456c-9fd4-b63e354bd324	{"type": "multiple", "timestamps": {"created": 1578614676, "modified": 1578615921}}
8c3be671-17d1-49fd-a891-d5e69fdf7fc2	{"type": "single", "timestamps": {"created": 1578614685, "modified": 1578615173}}