SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '298a4ec2f4a3fa38d4e32540a0a33843e92bcce5fca9c740c9061499a2badf93' 
  AND token = 'RpjfM4/BesqIRh8JQQFFBgmsiKBF4ZdgD4oDFoPMqPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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