SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f1094210ff591e284b205ecb2c8eeb480dc1e92693cc95534c015d6dabb6a03' 
  AND token = 'udnp9XM4pnOYiVgb0HTGRUHyoJe95nJg6UJWTINsULQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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