SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66e4b755b10aafd7368ee0e235fa8bcb23c135b1cd7096a2b432ced7487c2397' 
  AND token = '4+wmdFCqnJL7uNsuAroGQiGmC3NoHvDPrFU0zcyu3BE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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