SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dce34d492fa1a25145ee3a9cc2a76e43afcfc9cd2497687f883048edf6e6cc1' 
  AND token = 'w5ZLVEq8iMnqrFa9mT4iMHZXDLCReRQSsUQ0+KVJhgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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