SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14b6287e2a7ff68697abc308354d840dcff23a0237f35f94a82adc3dcc6d6c7f' 
  AND token = 'VLfi0pL1cZiMLuHqHclrC1LdA1QfjU8QvX7fLe2Hbgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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