SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3a465341daf12b0f23a04b397e69988a551c25d0d22a1271a98b766e0101755d' 
  AND token = 'mEsD9LBqf72sPyhfJJjEYzVGHPlWjfIvXCHHMiK+AvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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