SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21621c39548c82f47756fa16f289980f9e0b1d0c9e5101a847efc37b2f4d83dc' 
  AND token = 'GzCjktuKXQ+WxTyy9o2hcSBBpq9t/HoEnAEXrzxJ0nM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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