SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad183c12c0e29d8f90b4b6631f917a8932a7bede43ead582c729dc42dea90a91' 
  AND token = 'gWbETMQM4YrvK5OzIGZ+XtOgZ/ngVfMnU00hrLEX3Ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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