SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a92cf28b44b65f296ecd1efdd96da67fbf6bca04612847df9f7c967e56d1dc2b' 
  AND token = 'KjX+I3F2VUXWvK7UY5Tvo3ZfKHlzf6hVzUPOLw4t8gk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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