SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df511dae8b63c20e8238eaf665505f486dd636e3d5fc34bdd2f029d1d9422267' 
  AND token = '2bsrKJiNq8Kz6uiVJxTlleEjwlWeuBMgTYZcFvka6Mg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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