SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69708268a43832ba30b87b28f8d957aff6e8265d934835d325c3966fcae2baa6' 
  AND token = 'lf8s3RhYpWjlAkkYXv3hQOp65mjS7+lzp7W/WXagTgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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