SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '141e1891aec92556ed7cdfa4343b94f5c11e6356c20e7e76cf3d03f700c47a71' 
  AND token = 'n6xIveoRCMAKM3kjCM6FJ8bD298KqAOSDTcUaXGI9eY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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