SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83575ebf451c971a72ee875d31e1d6ae35c218f69682a8a9b2e47cc788cd5955' 
  AND token = 'e2mDzqY+I6JQf9qrMj0PRUlpSElQgPhPuPhRvvhG2DM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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