SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe82c4962c274fc49b35faf6a32db317f32baf222eff6df9118230dccd2bccf8' 
  AND token = 'MxjYWxSus2y1ZmvPnG5C5Is7+7sG5GiVuS40JHHaN3w=' 
  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"
    }
  }
}