SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18a3a682c549b0ad169aaa7bb8c35d85af9cde7f61a8f300621f31dc03a1b827' 
  AND token = '7H6eoEczOq2xQzKYliXMSHiw4aVsGzaWf81K/MADEew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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