SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8bf9922a5f193cebd83396024357514a30364e51297ca36946890ad2de8d8f' 
  AND token = '1pEyzVDtqF9TBl80MXXWgBGxiyOs7Hn92ZBH/qJVgFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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