SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1889e88921bee6d7091ef3e25ecef86e4c56ed3777e6d537d6d772f0cee76367' 
  AND token = 'KfhYT48oWZYgyTb6bdDjvnQllR/4qMGzS61VnthyMP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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