SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '685a6837885ffc40b94ea481bc18867e63567e683919db90e791a3e09b03e237' 
  AND token = 'lmXuPVwHfNg2CpWc+7LYOwTYRrpljFqN7DEvaX8uGTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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