SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '36338f8dfea725426a50f24198a07b478210db6684596cb0de27cc777518b9ef' 
  AND token = 'HmkjWv6mVhsdxX3dLalMmFcfmuf7KXnY+pBrvbHNkRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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