SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b55e9bbc591686666c402efe942a2dc0f73d43616a2f3ab1c5d0cddb34eea9a' 
  AND token = 'IjXi+6bxZ7LFJRBeW29YqkXZqoWmSxhUzhIcPLEYxoc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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