SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1744e142f7821814b3d9dce490a26225f1d984edf2d8486065a2704c544ab783' 
  AND token = 'oiRjsu3I7DQCYwPk9JVQdbxFpyskwpJPnnrHbUgdw2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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