SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6bb24d4275294139562bd4f247fa81a44b6f38a0f27e38afff036bcc244f970' 
  AND token = 'DLJIEeSMCi18YNvsg0eFtZXQCA8a3DZrHGUgF9nV8Ks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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