SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21043e85e761dc27b2aa126996dd80009c47b6d5e6f215e1ae1be0a66ec98ae8' 
  AND token = 'SGlkQHd/+mKGVxgLbZozDTr7h+Qcwquj1qG6mwDVx2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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