SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f1d24026edb3c080269e6fbccaa1d3f68151013e0e6a4e0cefec6bd4a71dc15' 
  AND token = 'lxi8PzaV4prsetrwFXdl24vYQp7H3jsonyW9emGnj24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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