SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56b381ae73de9f214eb81386a313e8e2a3a4f19361ebfb7b6eaead0e227986ab' 
  AND token = '/P2VzWQpIjBws6Ed02U/LcnfSJ5cBox7hvKZBk9li+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}