SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5db4916280a442672c9e16e25af7de969964130f1a19dd069bbdcfdeacfccff5' 
  AND token = '2rxXrJEPu2lmYMrdwBJmyCa4W6rwCzwVDwtIpAKrD0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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