SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '29a21ac9a79341d11c44dd436e228a70a06028a4514e7c5c189160646dbf9eab' 
  AND token = 'BDasKzVj1RQiWJDlACYH3QnkzZaTjF8wQEHRrX8N64Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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