SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7ac2314a5e1cb523b97008baf4864f4291616d0a8f0eae5fa42d0621ef506c8' 
  AND token = 'gQzcTg5JfrvR8zUNWNo2BUasjAQZ2qSX9ayMuytADxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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