SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '139598ccbab12acb05f68de0b8034090fe08e6f30eee54ec5f0c024ad951cc4f' 
  AND token = 'WncsXlNuQU9nd3AlqKZSsc5dfomopNmJFu4TxcvLrQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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