SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79ff24ec1194847ba944b33e0d6b7a228fb207019f68897f675978092a509e37' 
  AND token = 'Vu+z442H/CocB2pL+RhIpYgCW/jwBdVm2MhIR4wNjN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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