SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5048fed68285352d6a449d7754758fee0a113a2a71b906e241bbdfbc5ff1b68f' 
  AND token = 'Ou4AFUWc+xmNidRNVGvlh+znYsftbpKnTno20GVrfgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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