SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '921e58b5f18d394abebe0d152d74ee2666fdd5b6cb58d71051f600fd57e84224' 
  AND token = 'nOptaWb4wzei6rX82q+BQ0hVCq0b3FkS1uRZ3xc0HA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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