A parte de lo que dice @
cybervandal
Código SQL:
Ver originalSELECT *, MATCH (cupon_titulo, cupon_descripcion) AGAINST ('" . $busqueda . "' IN BOOLEAN MODE) AS coincidencias FROM cupones WHERE MATCH (cupon_titulo, cupon_descripcion) AGAINST ('" . $busqueda . "' IN BOOLEAN MODE) ORDER BY coincidencias DESC
En vez del AND va el WHERE
Saludos