SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea40b3d3314bed7f28b7215a64510bd44666195120a68fd4806b8f081ec7120f' 
  AND token = 'K8sEKXVdSu1gYrs+yZpDHK2nkuGObWABTm2h9iL6jhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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