SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a9efe7412d436931455bfd592169a1331453b9322a970f36cf93891a3feca6b' 
  AND token = '1+iY2ZwYODLvOjBYyBUjB0fWvHKOoQAqdjD8nIYyd6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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