SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c62a926073145572863b113b81453e103cd9d7c49b36548f268a0184a769764f' 
  AND token = 'p5CW6rPJNxwxVu8cfUKjVBGIiihgoYnwToaJSdsyfwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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