If you are trying to use the GET method to send an SMS and you get the "Error: 

error | 1009 | invalid key in query params. | 0 "error, please make sure that you are using all the parameters in the right amount and in the right order.

API input format should be: 
https://sms-magic.in/smapi/get?userid=username&accountid=8000xxxx&to=mobilenumber&senderid=abcdef
&hashkey=hashkeygeneratedfromMD5generator&msg=Welcome+to+Screenmagic 

Parameters For MD5: 
usernamePassword8000xxxx
abcdefmobilenumberWelcome+to+Screenmagic 

One of the reasons behind this error is the wrong HashKey. You can use the below link to generate the hashkey: