SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad3bd02c5ee78ed758989c917741bf7bc6fce4f91d1fd2f7667eea0fb8309eb2' 
  AND token = 'eDMYrCvxKG8fUJCibZ/mFjTfZoBqDCkH95F57b+ptWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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