SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2457fa3c9b63208b7cb540a80a1c2bdc4996eacddcb92991bf3fd782f9f4461c' 
  AND token = 'z/zKPTimgnD9L373L2XmRv8NSVQsIMVKCWbDtrjkmkQ=' 
  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"
    }
  }
}