SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dd7002ff126a9c277526542930c958df84dcd7111a434a70f1a6284cdd6e131' 
  AND token = 'sqdK/WpwQP8dwrsjJSIeFuRrKCIQOa/+MyHle30RzxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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