Usar expresiones regulares con LIKE para ordenar primero los alfabetos y luego los símbolos SQL

Prueba esto:

SELECT * 
FROM travels.destinations AS D
WHERE D.name LIKE '%act%' AND D.sold = 'N' AND D.active = '1'
ORDER BY CASE WHEN D.name REGEXP '^[a-zA-Z]*$' AND D.name LIKE 'act%' THEN 0
              WHEN D.name REGEXP '^[a-zA-Z]*$' AND D.name LIKE '%act' THEN 1
              WHEN D.name REGEXP '^[a-zA-Z]*$' AND D.name LIKE '%act%' THEN 2
              ELSE 3 
         END, 
         D.name 
LIMIT 10