SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1471e8fd18845890a12ec887230a71baa816854650360e54aa4e10078b53666e' 
  AND token = 'KtsgUqowijhaXxORIqNS8JAREz5XEf2ECfMkYLUFoK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}