SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '268efab08d836ad5bb4b5c322c372b248811b81a3a1fe34b826d1d3c38d98b22' 
  AND token = 'dxcwOWEMxXzaGu4nMOFgh0HgDo8FtWAoAJC2pA8qPOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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