SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9c6fadeaea83642ec130583d9b4d2a759539dd7e9c078cc4108b92c2c43bf2c' 
  AND token = 'q4gHc8zZonC2b/v9Vuj3mLhwq7kfqVcE6gcK+JVg8Fc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}