SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59bb128f82621c50d6e16136fcfc93ef7904e1359b677e95183efb9f1f082d34' 
  AND token = 'n9f0Jcay9yQr3YzWPT9abYDovqUsz63MS79FcbHdkdU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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