SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66b84ff2777a8023b3f1db659e7ef7fb063e43826331de55528268528c922168' 
  AND token = 'FnXXashG7HJyIIehVcgGpNi01w9TabSth4lG8xOfwfc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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