Impossible WHERE noticed after reading const tables

When I use explain it show me the below result

*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: NULL
type: NULL
possible_keys: NULL
key: NULL
key_len: NULL
ref: NULL
rows: NULL
Extra: Impossible WHERE noticed after reading const tables

mysql optimizer only work with data with match data.
else optimizer can't work

"Impossible WHERE noticed after reading const tables" mean mysql optimizer don't know estimated what index/ or it data should retrieve without data matching

MySQL Magazine - Issue 7

New magazine from the site

Issue 7

Performance Tuning Best Practices for MySQL

A video by Jay Pipes in one of Google’s Techtalk sessions recorded at 2006. A quit old talk but lot of useful information. Total lenght video around 45min. Take you time and go through on it