SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a3f1454a11d7b2d1f5f117ffd14658d504aaa3ea3d8198baf8bcb6fe86b57ed' 
  AND token = 'vlA677JUXiJTmEyuDCOyZTIkraBE/BWPM2ToAtLMSMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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