SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '671ca4055edc7ad4b86112be359c61033687d90fcc24f1c4d53f5b801cd022bb' 
  AND token = '9H8u56P3jhFG5JQDmJxB+qsbfQYZIJLGen7szLpTKis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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