SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f5b6c89d298e6c95db596a724e7a944649ab3e89b0ee15d02ba64b50c650abab' 
  AND token = 'JH0IjpeescciCIi5nmC0Nrj5nUcBnfqUWtsIOSRILek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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