SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a4683bbab87a67e511726ebebdec22bc3ced25e9f586cfd745ee916199df397' 
  AND token = 'MrATYVwjVXmZmfX6nak7251gPHwJ6Ak+UlPbCsVyKH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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