SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f1d44a2de9ca79b20a9ad9358cc2768699136c1e5a37fe2877ca614ce7c87d3' 
  AND token = 'DHgdkVoA60HNpcAZK0cr8dVHMvAXvaTNZhCSTxJymkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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