SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dc34ed9f43ed231ed794921e75b0d5e4c913898a7b51c94a4b7aa00728ce356' 
  AND token = 'jXu/x6eqq0fDmGab01s4KVGxpvQgzsS35ZoUBgWm3YA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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