SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504be6109b1536d52cb4c88f4e1cd589f4c1acb54b5e58ebbf2576671b866072' 
  AND token = 'a5jG936LM+JmVMnx+vkDw7JgmznWwvcQIPSt4dldV5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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