SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c9fb50af08ee36658deda008018ca84ece310f10deb25f9f6648267db1cb676' 
  AND token = 'v/TkOuelsW0guKBt/aazNoUBZ5lygHOd0FIjHKbNiAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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