SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d811e76999f916a493a3faa8eef9f40101647bfbaa456e3c33bc2d6319b231d' 
  AND token = 'QNe36vevWTJj5XDWysOQSyon9WPI8BX0n/hTjXaxK8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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