SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39b71927f7aafab66ef85a05e5fdc8a3244c288cfc39914904d238f4a14f5ca7' 
  AND token = 'WLfAZBuEHkCWhIVCrXRvUd6WyuwuInm9WqnQHRZtedw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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