SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cfc650254f2e3bf0685b32dd32e68214a97e16d323d70d00c35377bd90b87c9' 
  AND token = 'OyrieTydFtjeLItiZFGsnnDmaJbuMnDUVoYjwYMIvnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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