SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51030033eb2dc5389d954bd00250834432f215544ec79fd11bc0f216903adf1a' 
  AND token = 'Xf/q3gyNtOk7fwKa1IkgABYDFu7RggA5xTG1dIOXf/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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