SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ae101668d8dcf5ca2373f8870f9199dcfb29316f2aed16fa2bd198932f7267' 
  AND token = 'dhBZOb2AY8eK9bgyW1WOk3FBSIMLQJOa1on0IRqaGso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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