SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6ca023e2d77907b408dcafd23a3e92be1b1766e45b9684b3cde26150588a8b4' 
  AND token = 'jQjTtCu43+C6B2MaXhOKbpfeI7jyrVvNoiR5SsXtLj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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