SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '556841aa008959ac8731e57e0e86e5d4e75b906ce56a9a8cf4e6f38a92f425af' 
  AND token = 'GmpUwdg7KuZusvVXU/lBIjwVLOzBOTKAq+oLKKUvbiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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