SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e29c357fd4820857746f357a8fc50fbd00ed34be76bdc6a599d9b5f8c57f989' 
  AND token = '269YKZ3VpzP7QKh2u8goZ+03DX9dRGYnjvwMUPHYkXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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