SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '831f2e497ecbd640687b6746379085d782826326b7eabd4cc59d59a91cd4f48b' 
  AND token = 'ErnghqVMbm7MuCyvu1K6tC6x1BRCmH8krG0Jzh5UMyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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