SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31267a4cbf73c096992b830a4e93bb4e49305369a8f8f0acbb1721288294405c' 
  AND token = 'RLGAmFbEl/VS/IUMBo3snnJJ7OQ6WRkn69CVRy8Lt7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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