SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f5c6e39758f6a147c9b04a7c9e1911100528f447d11d8e5915fe19f09cf0391' 
  AND token = 'SH9vg0k1RA7mzV5gR+LdmWKjSo+/zGuiXP40kFaBit4=' 
  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"
    }
  }
}