SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d76eb4b788fba0e072b701475ff986ddb2089567e346694ab00c1f6be4ca515' 
  AND token = 'tYLZpY6Oa6hyq2SiDRxw6LjSXavaX8iYmWUeCKP2Qh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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