SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18db80634736771acb68a9ad6aa8d8d65f2b955d764c3b33f8bf6147d54fc757' 
  AND token = '9V2KvGZ7KbbCaBhsT6D3f0iNKIzjJsSFhrpB9uI/Ty8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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