SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1021c9eb825998d9dd4414d61c28082c259152a07ba28412d6c8a8237f83bf4b' 
  AND token = 'oUo77RcvQSR4HMGVK2+zgpKPlRQqdtvpj5925lrNtNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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