diff --git a/framework/yii/db/BaseActiveRecord.php b/framework/yii/db/BaseActiveRecord.php
index 6c947b8..e20501b 100644
--- a/framework/yii/db/BaseActiveRecord.php
+++ b/framework/yii/db/BaseActiveRecord.php
@@ -1234,11 +1234,10 @@ abstract class BaseActiveRecord extends Model implements ActiveRecordInterface
 	public static function isPrimaryKey($keys)
 	{
 		$pks = static::primaryKey();
-		foreach ($keys as $key) {
-			if (!in_array($key, $pks, true)) {
-				return false;
-			}
+		if (count($keys) === count($pks)) {
+			return count(array_intersect($keys, $pks)) === count($pks);
+		} else {
+			return false;
 		}
-		return count($keys) === count($pks);
 	}
 }
diff --git a/framework/yii/validators/UniqueValidator.php b/framework/yii/validators/UniqueValidator.php
index b04f4a9..53b6739 100644
--- a/framework/yii/validators/UniqueValidator.php
+++ b/framework/yii/validators/UniqueValidator.php
@@ -55,7 +55,7 @@ class UniqueValidator extends Validator
 			return;
 		}
 
-		/** @var \yii\db\ActiveRecordInterface $className */
+		/** @var ActiveRecordInterface $className */
 		$className = $this->className === null ? get_class($object) : $this->className;
 		$attributeName = $this->attributeName === null ? $attribute : $this->attributeName;
 
@@ -67,6 +67,7 @@ class UniqueValidator extends Validator
 			$exists = $query->exists();
 		} else {
 			// if current $object is in the database already we can't use exists()
+			/** @var ActiveRecordInterface[] $objects */
 			$objects = $query->limit(2)->all();
 			$n = count($objects);
 			if ($n === 1) {
@@ -75,7 +76,7 @@ class UniqueValidator extends Validator
 					$exists = $object->getOldPrimaryKey() != $object->getPrimaryKey();
 				} else {
 					// non-primary key, need to exclude the current record based on PK
-					$exists = array_shift($objects)->getPrimaryKey() != $object->getOldPrimaryKey();
+					$exists = $objects[0]->getPrimaryKey() != $object->getOldPrimaryKey();
 				}
 			} else {
 				$exists = $n > 1;