SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50b03ab9d136feacd1162c2ded57da749e68208b2d2291e0fb5426ebbf9926ca' 
  AND token = 'uwISjyNVh5Qbwat0NYgWCDTUFtr/9rhOKEg6gtYRPPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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