SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81fe519be8ef818cfeee6e515265c167078f0894a5b62b4c75a6697698d125fd' 
  AND token = 'jlkKuc3TlJR9YRfdfl0IaNevYum94iuhm0YMYc6JW6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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