SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e6be5f731ebcb18e5f80f68eca276a82f74b3588fc45b2ba3914f99f561def4' 
  AND token = 'dZcIbzEVMNt0aX8/dVNFpdmvJ5VT+BDYnPGOqWYiU84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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