SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2539967ad3a515aab7f6e6822dbf67d7d472912b498321600f6d767734471364' 
  AND token = 'xLeG0+/zrYqT0cMWNsPzy3mwgVRzGIKlnkGlf8gNJBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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