SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b566daefd94d9663ef30152fc8eb48177a6c1a839575f4e387acffc0ecde38ee' 
  AND token = 'hJ1xN+v/ZsnsvnFtKyk/zBT53VAZKT1vlxVQHobkOLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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