SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8004c9699cc620f136c55896787e4393a36cca4b42e5ba34ba78fbeee46d802d' 
  AND token = 'bOurergbW7Gx1IbwmJoSizezpiwPD/z+emhuaypSAQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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