SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f31484bb059a8aea900fcd7a3f853341055d0d4f9a6a194b96bab04a3f02dd2a' 
  AND token = 'Wrc5USYIpiJ6i64h3bWnkFomLRDHXnP/4MavcaZ0pTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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