SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd45321fde4348991b7b54993b8175d5a8a1a561d1e0ad89f73909504b536241' 
  AND token = 'duoiQOx0ClwKbVGKCZzKoP0KmuRjoRhTBgU3/xjFqJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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