SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fe4d238acf9a2557330886eb5fb109d8b9dba82923f346d688060c2a863426a' 
  AND token = 'x8YEcuBDgt/HkZbsfmOwqWgn8wvuIxKb4EySCzGVv4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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