SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c28253f9a689264d65657269f7962f533a94782bffdb061a7d362cc20c51915' 
  AND token = 'Sf8j5IeO1BJmCt/Rh1XQbJunpzX+vweOKIssPY/NuxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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