SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d789c47f8fe689951747707a49d45a20f7a307f7ee9842ad5326e4c86418725' 
  AND token = '1nCIfzvWwCDFxytT5RcxBEUaZuGWTF1YhvdDpIXeBBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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