SELECT 
  1 
FROM 
  tmall_lock_keys 
WHERE 
  key_id = 'a3256029e6a02cf75e977e5c19be75f3d0ffb13eaa38cdc52bde85f2bb499c4d' 
  AND token = 'C6ZxvRchtg+/PYYv1HcnlHFT3lK/wh3QyaGvGxLWJiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00803

JSON explain

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