SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '083ec30d5303ee6cf6db1ec4ab6c0d1ef6525889ab76bb9bd4211600180bad43' 
  AND token = 'oWJ0l5wjdjMHJPsD1wx2Li+CWpqcdkqeDvgGAHBHkjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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