SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bfed35b53ee92c9ca02e50c45d7f94121baef0308eeba6d8d45b90aa7c3233ff' 
  AND token = 'H2/l/niISjsDtPakyYjwhcqplox4I+pj6FiuNz8/P64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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