SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c423d231ac72dec724d3c8886a4ea91d06c1f1cf063fe51ab1b4c47c54233b6' 
  AND token = 'u3JDx5Pr2UDQpEYu4Zfx/CkiYQMdtbQhikOY+rF7F3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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