SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8a4f051b71fb0263ac762463578bc307fd82e24fe4d50e24a9272718ab79d76' 
  AND token = 'HwcS75DG/xq+3JcLSVD5UWmf5oiUHvOJVdZIcvHkLi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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