SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a2a6aa59870580f078cd1ed2c6d87ad21fa8bd023ae373099e6dcdf5c7fb2df' 
  AND token = 'u+dbTiURWL6QGw/ahTDRIIFMO9J5lHGVoj6j010oQBM=' 
  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"
    }
  }
}