SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '23d92953a762d877e17b1fe53a5b347a7ba6b1da7754f5cf93fcf0299509a382' 
  AND token = 'ffVnGAqIg16a8VjLD0TTCRFxjfhUPloPZRwjb4dtCUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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