SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bda1bd1c50f9866d273877fb7a7b704503d4e87a5119d621a2cec9e1fe44ff8b' 
  AND token = 'BuGIIC/B+JQTFVYV9cM0Xed9IiDOpsVdz+jd3ZoJDWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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