SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dc56a34449e72b3c148a80e821873024936aaa1692220f2fb251e271de778af' 
  AND token = '6d/ONRuofg1jxRuoD2rlOxD8CsWpA6J1Y8jw+0KTbW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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