SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9f2f6d4627b4099918cc449b630914e813d77e7d32fb64640e126119af292e7' 
  AND token = 'dHMcQyixdv2oRa+z417/Pxw29Ki9ySbZo3wh6rXnlRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}