SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e0b3aec040e901d8669095684a276080a21b8db41937dbde835a32fdc47448b' 
  AND token = 'qhkjipcSp1HbmZ/i4wmLfqpZdqVgUavpNvrMrBGjORw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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