SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ae76b8e07f8e6804ba39926a9db562af326903ba350e313beafabe9f960e163' 
  AND token = 'houw+tLAAb+4yofW2Esfy3GiXcZZ2IeO9dvbGTSwmD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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