SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '471b38eb3f88c16d997aafa23381d0db2f2dffaee0c566b78500a00a3f552872' 
  AND token = 'dGL9aMyaOVPXfoBWz+8HjhgwsW8mrnK7zjWnmDWY66g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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