SQLSTATE[70100]: \Unknown error>>: 1317 Query execution was interrupted

I am trying to execute this query but giving me this error: I will change a column from not unique to Unique. partner_id is a foreign key. N:B: I am working in Laravel 5.3

class ChangePartnerToPartnerFinancialInformationsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('partner_financial_informations', function (Blueprint $table) {
            DB::statement('ALTER TABLE `partner_financial_informations` CHANGE `partner_id` `partner_id` INTEGER UNSIGNED UNIQUE;');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('partner_financial_informations', function (Blueprint $table) {
            DB::statement('ALTER TABLE `partner_financial_informations` CHANGE `partner_id` `partner_id` INTEGER UNSIGNED NOT NULL;');
        });
    }
}

Full Error:

  [Illuminate\Database\QueryException]                                                                                                                                                   
  SQLSTATE[70100]: \Unknown error>>: 1317 Query execution was interrupted (SQL: ALTER TABLE `partner_financial_informations` CHANGE `partner_id` `partner_id` INTEGER UNSIGNED UNIQUE;)  
                                        
  [PDOException]                                                           
  SQLSTATE[70100]: \Unknown error>>: 1317 Query execution was interrupted