SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84800c0d384091544164d2992fc54ed50599b75d2da6548388ef7a8009ed070d' 
  AND token = 'DOlclZrE4i2xZ5eMqRkrzJ1yku9Wskgd7EzhsuAEn9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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