SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d03234a7edc151b72b25e0eaf83ccf808b828bbde5344f7777b73475216dad3' 
  AND token = 'teE+a84rqqZmAEJSC42+UQ1sbeJFsoomldoNYsLYBZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}