SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2400ecc89f644cc8611d775878efb54b7e80bff3b6632f35662059fbdaa80e56' 
  AND token = 'tj8xti5PFMktOqfTW4fFUQDaUE0kxoEKVVKxhlwBJzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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