If you buy an unlocked iPhone from Apple the same can be used with any carrier (Cellular Service Provider) around the world. All iPhone models are world phones, so you can use them almost anywhere. Whether you are a GSM or CDMA network customer, you can roam internationally on GSM networks in over 200 countries or regions around the world. Availabilitys of LTE data varies in some countries or regions and depends on carrier support for certain LTE radio frequencies. Contact your wireless carrier for more information regarding international roaming policies and rates.
However regarding BoostMobile Plans and Services and any compatibility issues, you need to discuss the same here --> BoostMobile Community Support