SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdd9b18d57210f6bfe11c520bada34551f18d132def77fec759fb4ccb4a812d7' 
  AND token = 'BFuK1eirT+5gh89mJsdpfD8VxLk99KqmvEQsBx/+cBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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