SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '189297b3e29d065968f62ec9defd2f5e3ddbc7d9b0fbf7595c0a55449bda0510' 
  AND token = 'Wd4qmTsM76AjF98OkiN9sB9LFUIdcsNejKCgTvWOMIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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