SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a2715d56022e14488ed15315dae4081e142e85f536d3512b7b0634928be52634' 
  AND token = 'kZgzhUXsOuroRYjhm61pXIqNh8EduutdGXG3SJflLbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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