SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79afe329a0feac7c64cada878d8cd3a6afb6c7aa5f679028979af6f2a5a9f4fc' 
  AND token = 'xVv3cgZhg7B5NmYDnzqhG8dFjWlN86QD7OFwaTxpCAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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