SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea81854f80ba9ba7b5a5cb4a55e36353467a8819aa8733ee285de415ed478ace' 
  AND token = 'EXX7qovySpKFx3dEA4sm7uou6GZj47S1ZxyqDR6y5Iw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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