SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9eec1156ee6c8480afa1c2d62241baab924d06a814d140469c5fc99a843fc355' 
  AND token = 'k11RnbNXDSVACiqVwI/+cR6ruQNJoSCh1RMfapw9UoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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