SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f3505947f4d8aa1b0db51bce2080a56e6d31fda46e5828fffe1efa7db9169f88' 
  AND token = '3c27j0K8gf2F5dHQZQmyWNATeK6POG+mqn4HYWxn5kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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