SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6de889cb997e96ca94d36359f40459d4a7de5368063124e8d928ddb535be28fd' 
  AND token = '/n8KJEkuaXxZZhlnwesXRh5kErFFxHiFqZd8PVB/EmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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