SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ff15f9aaff7897cbb7a4a7697a7193b5b0d64c66eeaecea7e69f0f9e809b07b' 
  AND token = 't152KgSB9sxgy4PAUfYRbyRuXMWTeTQL8sZw7eWt0uY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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