SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '193b2625aecfe82468b172e33c847c93b5579adb7e3740c9d9afb478031fe3c2' 
  AND token = 'EemVo2QP5VDJAdm3mc38PJyVHqjySkrr4RwDCMtIGbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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