SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0596c51873fd1861f70f0fc7f8aa489b0660591b47408b630b45f9dde24c9342' 
  AND token = '6Frd41PnYCqmjgmiN4oF+szCqvZ0kepHTmnuCFq3goU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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