SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b0386863ab10527c251c536d1f503ad2ca55fbe49879ec819fff7e171efdb68' 
  AND token = 'gSfwhkM/w4jn5gPObQ+NcH8DwqI+F9cqs29tGmVNwFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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