SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '90ae9284fb9916525f8069b72b5007aa6517419d1454b7d533227b709f91c964' 
  AND token = '4651l8UxljEFmJ3GyITlaNyvXLMEGbR8VRzFhCbQwoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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