SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c5fb5504c5f9deb6268e44c36c13fc009b8262ea05915253f9f87c848303d748' 
  AND token = 'kr/v5gv2CxpXLwpribN6z3qhUkYIqqgWDue1hXZBiDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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