SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9b050eaea00738e7cb09ddbb5585d92f29e20be773be1d3db853d8cb85d059c' 
  AND token = 'tnnb6wNGIzLtXwZ9g7xgduPavQ3tUzsIkarw0FdbH1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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