SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e620fec3abd69fa1626babb346b709cf30d77fded41b50fa465857165dfdb395' 
  AND token = 'vxcU/QfuBnhmUKRgbPO9iGx8qowSGw8rZCEPVSfxVIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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