SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e2b2242393890b52a8d2cea2290f3cd83578c2a4fd111ae8b6b62b33ae4a5eb7' 
  AND token = 'ojNBeNWXqhVGcqlUzXVVJg+akMskpBsMWpNYIMtFLC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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