SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4552a416a30978c69e17cad2b8d674c6fa40a78587bdd8a2058b855fb41bf71a' 
  AND token = '1MDbErPjVPSJeHXJlgbDVbEwxb1Hdrvqo7p4jN02UIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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