SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73cbe270a2107cd423c6a168f8736517b434c781f2c1b3bd73d550ad1635924a' 
  AND token = 'JOq5HGxzUw6dnGOz/9KtBgWrvfc1cd4XcgYW7Nt0VKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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