SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b7a43c85289b73a7e561d5f4d98ee07b074fca782c69dc0807c64fcc6f25c5be' 
  AND token = 'LR3uIYsD2qoomh9J7gPzSR7wrwwVGUWOzE8FlzQkzwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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