SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3b5e1643929a926200416c309da76e53c71780f424491140a55abb15bd3bd947' 
  AND token = 'ADOR9iG4gvxYERJ4Y2mmx9gi8Zv54DutLeCXZn1IRFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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