SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '815f067929355c5e7ed4c391bc62aabe601cc99d91b4a8515a79020c50ce0f5f' 
  AND token = 'yFhWtTHrZXDSpGOtVKXEtnmv7qQ4/PDYKKKJaeNaAGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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