SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c50669b03900aff2a0098b95c386b868e22dbb073b5b444ffbceee6a8d9f42' 
  AND token = 'Wwl+K1maamLQzX5wShh8QrIKjQK7K2XDlFXkFYmtDyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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