SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df4f1a48442751305e8ee66f80748e5a75f64d0f62aa32b39eb60ae1b8650487' 
  AND token = 'DVw5OLcsWLOJdMHki5/jPsKsJ7YzCl/CEFd8Fjhwb9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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