SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd59835183dfd2aeaed70c40a774ecc8c006a39dca3af62add99720683acaa31e' 
  AND token = '3CvD3xMVC8rCNKbgCD4yAjCYVwvSKvT+soCovvYWiss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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