SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '377a4fb52ff4cbc5e2f4c9584d7b71c90c5263a43aec061bb528b7921806e306' 
  AND token = 'eYmnVQOnuaFXWDhHV8PRUncYKCLpj531dP9x57QQo1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}