SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'def5685a3f19fccf5902caf6baa75a91b30d524d3a455e74e01b3d391df81cca' 
  AND token = 'JV8KXzO7TfRyMULE2B9H7KmRyB7bp7XxTU0UsqM25BE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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