SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1dff957231871b780273065fc28c0b46ceef3e49a5cadcc156493964142c52ed' 
  AND token = 'piWchlU0tmynWk7zj9Zq9zyEv59kHOgAphbAB4KvNJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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