CREATE OR REPLACE TABLE t1 (id INT PRIMARY KEY, b INT, KEY k1(b) IGNORED);

SHOW INDEXES FROM t1\G

*************************** 1. row ***************************

        Table: t1

   Non_unique: 0

     Key_name: PRIMARY

 Seq_in_index: 1

  Column_name: id

    Collation: A

  Cardinality: 0

     Sub_part: NULL

       Packed: NULL

         Null: 

   Index_type: BTREE

      Comment: 

Index_comment: 

      Ignored: NO

*************************** 2. row ***************************

        Table: t1

   Non_unique: 1

     Key_name: k1

 Seq_in_index: 1

  Column_name: b

    Collation: A

  Cardinality: 0

     Sub_part: NULL

       Packed: NULL

         Null: YES

   Index_type: BTREE

      Comment: 

Index_comment: 

      Ignored: YES

SHOW CREATE TABLE t1;

+-------+-------------------------------------------------------------------------------------------------------------------+

| Table | Create Table                                                                                                      |

+-------+-------------------------------------------------------------------------------------------------------------------+

| t1    | CREATE TABLE "t1" (

  "id" int(11) NOT NULL,

  "b" int(11) DEFAULT NULL,

  PRIMARY KEY ("id"),

  KEY "k1" ("b")

) |

+-------+-------------------------------------------------------------------------------------------------------------------+