SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94f4593fba4f87301aad14364a96e163267843eef638d9670c3bb077991ae935' 
  AND token = 'n78Lvzz5N/GU7Yk+Y6jpTaQqTP5dhrcZght16qVay/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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