SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77d4009ad9aa9a4c8e81b0d8b6b486c04efdfbea61937986d80ee026c3099922' 
  AND token = 'EKaogw6fBEKPiaJj8Htfz7yiTf1kg4wwBIrxU/XineQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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