SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16b68e85486fea9b5fbf21337907d9dfe12f666d58cecabd3c744a88607ef60d' 
  AND token = 'zEYYK4ag2Hma2UZGRnBlLlmEobus4+NZBuCOgHOqeXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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