SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '603e2fad11a9bee42fe12b4bee54cee83d24de4e453608241d703ba5fa72513a' 
  AND token = '1JdOjRGrgq/thyCdMOS7wPj+Ynodi0AVr76Yj6Bl3eM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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