There is no specific token check endpoint to validate a token. But you can use user info endpoint to validate your JWT token.

Send a get request to /realms/{realm-name}/protocol/openid-connect/userinfo endpoint with authorization bearer token in the header.

if a valid token it will give user info,

{
    "sub": "xxx-xxx-xxx-xxx-xxx",
    "name": "John Doe",
    "preferred_username": "jdoe",
    "given_name": "John",
    "family_name": "Doe",
    "email": "john.doe@example.com"
}

if token is not valid it will give

{
    "error": "invalid_token",
    "error_description": "Token invalid: Token is not active"
}