SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa8a890e7b75df4b081bd8eb5f47380d2f2efd3dd63561197fd16dc475fe7c6a' 
  AND token = 'GDNpe+xowcuawwMQ97FyRJFEgB3PbLZ9vWzDujK1SsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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