SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b6f16a4808ba1010b47d74f3bae55e4e9eff57955ce48c90195b91b563152087' 
  AND token = 'CpW86AOPdxiP/ISmhnSyxd9n+vqhRdiHsU8PkRLyeUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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