SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52a7e9955b6c4cb58ab1752a07b87f949f722047811bfccd60323000f5382ed9' 
  AND token = 'cF5QAEWgV3SvllO1mcvkmQeqTc7YNM4GEY+8W8S4KkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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