SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0a769537690134875b47e48790d736b56d605edede9a088d25cd17a979d1f4a3' 
  AND token = '/x26CAjPfV8MILUA+QJuP0SZZUB/NaKfRCzbL0eQf4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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