SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0d17ee37586f1f9b2e89535baf839492c41ec0bab58b992febe4f89dec0a7b95' 
  AND token = '6qHgl3+4JAWa3dn2wyVemWaYmEnkk1mNnIkVrqkcCUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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