SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cd4b41021a1442624979365df7f847fb319227c13498c7f8f90729a08775033' 
  AND token = 'vViA/pLLuGmKDKHps7wOztXGLYA2nTUD6mv0p6gmD8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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