SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6485c185daf130dac6d54447f967f7318b537b66a33a4379ce1b501caca692' 
  AND token = 'sX/Ku5evGDlws1hx1VWRYqbMuAb0VXiBvDbgkhVBkWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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