SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ad853bc847a360f66a622df3251b5e10359699fcd69427bf525a02577f84548' 
  AND token = 'RBlp9qPO4l8s2n3wkf9C3xoqvq/UqhdRAZqj/+tXvcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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