SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '171212c13d03cef5e94a1d423483539533135933f7ab615bd62feec0835b29ec' 
  AND token = '06qMdtjvTX1cl9ohUkyljtwcj3KZ+UTppH4eBByGVxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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