SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9e7d566e8e78b8f1f4b428d23cf8e4ac22bf435c939ef0f6ef59af788bb0d56' 
  AND token = 'TSx/OvBUd19rWMYKudQHKqT8oGBGljMbXsq/mAqiN3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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