SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '16f08c6de8c7975279eeb523f421ba20dc232bb0c5c7b394e225c361cd652548' 
  AND token = 'UzCJdcB+g7sfJn3qgpKw2oNJ4YxwoATJR7iJVQBK36o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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