SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1f604885882fb48d5c0723e7c749af40eab31861fc3b9c4363ddf5a32b75a5c' 
  AND token = 'ubFggKQKQxottdJ+B6K+exZpy0twAmPzG2IXCzDBlNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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