SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '049fc862ae47f8156cc83f630010e7eec373e428a346697a88289ba62a8a6836' 
  AND token = 'sbVfED02yaMYBsObaBc2MCPfzDNgdPkMzfo1bpsmxwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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