SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23713371958ea7a61c906247580f6931d08701995c4ba54b71f712ead4e9167b' 
  AND token = 'K5z8/Sz40cWExg0ysSKGoVuZtDIyq273zVkWaDuObeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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