SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '00d12b1f56e84c7e86275d19b7ee56bdcadf86e6a08b410ce7cd10efe97de608' 
  AND token = 'ib7iefPKGYgso/WrUoPvvoiyYp3CDJBvandQb+spvlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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