Inline encrypted variable not JSON serializable

Add task-level variable:

  - name: Create 
    mysql_db:
      state: present
      name: "{{ mysql_name }}"
      login_host: "{{ mysql_host }}"
      login_user: "{{ mysql_user }}"
      login_password: "{{ mysql_pass }}"
    vars:
      mysql_name: !vault |
          $ANSIBLE_VAULT;1.1;AES256
          39613261386438623937643062636166663638633062323939343734306334346537613233623064
          3761633832326365356231633338396132646532313861350a316666376566616633376238313636
          39343833306462323534623238333639663734626662623731666239366566643636386261643164
          3861363730336331660a316165633232323732633364346636363764623639356562336536636136
          6364