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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6ec7e17d123727e85f7989adcd7a5d83c8b78470e8944e713b28afeeeca9739' 
  AND token = '3JEHe9qS6Uzy14SDz0c77guSZK0Wp7s/7dm4UM1r+6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}