SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '016f94b5049d67e69024cee37d9a4826f77b20248d45d2d4139e7026df218e82' 
  AND token = 'ajhCWzqFbLuQA3d0UTliJRpx8rabP8XlZy/SSbcpRSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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