SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8b76ca8259351e135eeafa35af74598517c1e00dc8e278180caf27cbe5e60a03' 
  AND token = 'dVTuKny/CZDHY9yAhJLfu6fpn7oZU67PofChHXOmFak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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