json passwords security

Is it secure to send username and password in a Json object in the body of a post request?

I am building a web application and my web server is secure, meaning that it uses an ssl cert with the front end to encrypt the connection.

When a user logs in, a JSON object which looks like this is created, and sent to the server.

username:"the user's username",
password:"the user's password"

On the server this is verified with a hashing algorithm that uses a salt. Once it is verified an api token is created which is valid for a certain amount of time, and is passed back and forth in the header in order to verify the user when requests are being made. Is sending the username and password like this best practice/secure, or is it better to send it in the header?

Lets divide it to many points:

1) you use a valid SSL certificate to secure the communication between the user and the server (It must be valid)

2) Sending the username and password in the body of the POST request is the best practice (Never use GET to send sensitive information such as Credentials)

3) Sending the api token in the HTTP request and response headers is the best practice (Again never use GET to send sensitive information such as session tokens)

So based on the points above, it seems that there is no risk in this implementation but you need to take the following points in your consideration:

1) The time out of the API token should be short in case of idle user. (5 ~ 15 mins are the averages based on the criticality of the application)

2) The length of the API token should be long string approx. 30 ~ 40 characters.

3) The API token generation must be randomized and hard to predict to protect from (session prediction attacks.)

Hope this help you.