SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cf85fcbb3866d24703e877e30c567c40aba44f8270be8bfec998fc2693b1def9' 
  AND token = 'HwZdzyBdWL24v1ih4gKm2fFLlwKYuQQHn3W3VWRY+EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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