SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '843e35df519fdb9fef5f534b4bdae9ef89b924d45ce35171beebbe66a91e30eb' 
  AND token = '70/6TGp4OoC/J5r8rYEbAvN0y9MqylAP0tIMO5uvC6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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