SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b3985642de96a8e266ce1a62198b604b7a8c64ba139be69e1cfdf4ccfa631e0' 
  AND token = 'KPN2kVppqZKYzAsDqJk/jQdUT1wWc9JFL1qWq9F86BM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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