SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bfb87d020d202033532375aff342d4a06422e8cbdcb1e046d5258d80c59d476' 
  AND token = 'YCz3gHwNKjVA3B/gLDvd5lt2czbjEf/LDJ+iYoW7caA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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