SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6281a7af00ea228546c1e56d83bf565a4c2947e0c82aad0f409419aa46adcd81' 
  AND token = 'IwRHlseUpRUP/jfJYu8sUI0zSlWAIkgDMPW2g0qnXN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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